J Cutan Pathol 2014: 41: 950–954 doi: 10.1111/cup.12412 John Wiley & Sons. Printed in Singapore
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Journal of Cutaneous Pathology
Interface dermatitis along Blaschko’s lines Linear dermatoses are fascinating entities that likely reflect embryologically derived cutaneous mosaicism, even when they occur after childhood. Adult blaschkitis is a rare, relapsing inflammatory dermatitis that most often presents in middle age. It presents clinically as a pruritic eruption of linear papules, vesicles and plaques, and is most commonly found to have features of spongiotic dermatitis on pathology. However, the clinical and histopathologic presentation of lichen striatus in adults may be similar to those of adult blaschkitis. A case in which ‘blaschkitis’ was suspected clinically is presented, in which the biopsy showed non-characteristic microscopic features resembling erythema multiforme – a finding rarely reported in the literature to date. We present this case and a brief review of the most commonly acquired linear eruptions following Blaschko’s lines with the goal of expanding the histopathologic findings that may be encountered in adult blaschkitis. Moreover, the clinical and histopathologic overlap between the entities of blaschkitis and lichen striatus is explored, acknowledging that these entities may exist on a clinicopathologic spectrum. In the diagnosis of linear eruptions, clinicopathologic correlation is important for arriving at an accurate final diagnosis. Keywords: blaschkitis, lichen striatus, linear, interface, spongiotic Johnson M, Walker D, Galloway W, Gardner JM, Shalin SC. Interface dermatitis along Blaschko’s lines. J Cutan Pathol 2014; 41: 950–954. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Linear eruptions are an intriguing group of diseases and can be dermatomal or Blaschkoid in distribution. A dermatome represents an area of skin that is innervated by a particular spinal nerve (with herpes zoster representing the prototypic cutaneous disease expressed in a dermatomal fashion), while Blaschko’s lines are thought to represent migration pathways taken by epidermal cells during embryogenesis and fetal development. The diseases expressed along these invisible lines of Blaschko are thought to reflect cutaneous mosaicism, with epidermal and dermal cells within that line expressing a common, post-zygotic genetic alteration1 – 3 .
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Mariah Johnson1 , Daniel Walker2 , William Galloway3 , Jerad M. Gardner2,4 and Sara C. Shalin2,4 1
Department of Dermatology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA , 2 Department of Dermatology, University of Arkansas for Medical Sciences, Little Rock, AR, USA , 3 Russellville Dermatology Clinic, Russellville, AR, USA , and 4 Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
Sara C. Shalin, MD, PhD Assistant Professor, Department of Pathology, University of Arkansas for Medical Sciences, 4301W. Markham Street, Mail Slot # 517, Little Rock, AR 72205, USA Tel: 501-686-8007 Fax: 0501-526-4647 e-mail: [email protected] Accepted for publication July 20, 2014
Report of a Patient A 47-year-old white woman presented to a dermatologist with a 2-month history of a unilateral linear rash occurring along Blaschko lines. Her medical history was notable for depression and infrequent outbreaks of herpes simplex labialis, although she had not experienced an outbreak temporally related to her presenting dermatologic complaint. The rash first appeared as red-brown papules, initially located along the abdomen, which coalesced into linear plaques. She later developed similar linear plaques along her foot, ankle, axilla, and arm, extending to the fingertips (Fig. 1). The lesions were pruritic
Blaschkoid dermatitis
Fig. 1. Unilateral, narrow, linear, red-brown papules and plaques distributed along Blaschko lines in a middle-aged white woman.
but otherwise asymptomatic. Her only medication included citalopram, which she had been taking for many years prior to this rash formation. Direct fluorescent antibody testing for varicella, performed by her primary care physician, was negative, prompting referral to a dermatologist. Upon presentation, the dermatologist clinically considered adult-onset nevus unius lateris versus an acquired linear dermatitis and performed a biopsy for confirmation. She was treated with a potent topical corticosteroid to help relieve pruritus, which improved this symptom and also lessened the erythema. Subsequent to the biopsy, she was presented at the local Dermatology Grand Rounds, where her clinical and histopathologic findings were discussed. The clinical impression was felt to be most consistent with adult blaschkitis given the patient’s age of onset, truncal involvement and accompanying pruritus. Histopathologic examination of a biopsy obtained from the left flank revealed the presence of interface dermatitis. Numerous apoptotic keratinocytes were seen at all levels within the epidermis, many of them adjacent to infiltrating lymphocytes (Figs. 2 and 3). Within the dermis, there was a mild lymphohistiocytic inflammatory infiltrate with vacuolar interface changes along the dermal–epidermal junction; the eccrine glands were without significant inflammation (Fig. 4). The histopathologic features were most suggestive of an interface dermatitis such as erythema multiforme, but, given the clinical presentation and the lack of triggering factors for either erythema multiforme or a linear fixed drug eruption (FDE), the findings were
Fig. 2. Scanning magnification reveals a punch biopsy with interface dermatitis. The deep reticular dermis is spared of involvement.
Fig. 3. Numerous apoptotic keratinocytes are seen within the epidermis, many of them adjacent to infiltrating lymphocytes. Within the superficial dermis, there is a lymphohistiocytic infiltrate with an interface component.
interpreted as compatible with the clinical impression of adult blaschkitis, albeit one with an unusual microscopic pattern. Approximately 1 year after the patient’s initial presentation, she reported persistence of the linear eruption, with periodic flares of pruritus, which she treated with topical corticosteroids.
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Fig. 4. The eccrine glands are without significant inflammation.
Discussion Linear dermatoses represent a fascinating category of cutaneous disorders. Linear eruptions along the lines of Blaschko, in particular, may be congenital or acquired. Incontinentia pigmenti and variants of epidermal nevi (inflammatory linear verrucous epidermal nevus, linear porokeratosis, and linear nevus sebaceous) are examples of congenital blaschkoid lesions, which most commonly manifest at birth or within the first several years of life. Acquired linear eruptions in a blaschkoid distribution may be common dermatoses presenting in an unusual, linear distribution. For example, psoriasis, atopic dermatitis, lupus erythematosus, FDEs, graft-versus-host disease and even erythema multiforme all have been reported occurring in along Blaschko lines4 – 9 . Other entities, namely lichen striatus and adult blaschkitis, routinely present in a linear pattern. Psoriasis is a chronic, immune-mediated, proliferative skin disorder, which clinically presents as scaly erythematous plaques and affects about 2% of the population6 . Linear psoriasis is a rare subtype of psoriasis that is distributed along lines of Blaschko. Characterized microscopically by acanthosis, confluent parakeratosis, hypogranulosis, and intraepidermal neutrophils, these lesions are usually asymptomatic to slightly pruritic and respond to conventional antipsoriatic treatments6,10 . FDE typically presents as a solitary erythematous, oval patch on the lips, trunk, upper
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extremities, or penis and develops within hours of exposure to an inciting agent. Lesions resolve within 7–10 days but characteristically recur in the same location when the patient is reintroduced to the causative drug 4,11 . A lichenoid dermatitis with orthokeratosis, mixed dermal inflammatory infiltrate, and marked pigment incontinence are seen upon histopathologic examination. Very few cases of linear FDE have been reported; these documented cases include reactions to naproxen11 , trimethoprim12 , cephazolin13 and calcium-acetate4 . Atopic dermatitis may rarely present as a linear erythematous, papulovesicular eruption along lines of Blaschko in predisposed atopic patients, with histopathologic examination showing a spongiotic dermatitis 7 . To date, only three cases have been documented, including an 8-year-old girl with involvement of the left arm 14 , an 18-year-old female with involvement of her right leg15 and a 36-year-old man with involvement of the left leg7 . Linear cutaneous lupus erythematosus (LCLE) is a rare subtype of cutaneous lupus erythematosus which usually develops on the face and is most commonly seen in pediatric patients 5,16 . However, cases of LCLE occurring in adults and manifesting along the trunk and extremities have also been reported 16 . Biopsies of discoid lupus lesions reveal basal vacuolar change and interface dermatitis, with epidermal atrophy, follicular plugging, dermal mucin deposition and a periappendageal lymphocytic infiltrate. Of inflammatory dermatoses that routinely present in a linear fashion, lichen striatus and adult blaschkitis are the best described. Lichen striatus is a cutaneous disease of childhood, presenting as a self-limited, usually asymptomatic, linear rash with an average age of onset between 3 and 4 years 17,18 . Lichen striatus usually appears as an eruption of small erythematous papules that coalesce into a solitary, usually unilateral, narrow band on an extremity over the course of several days to weeks 17,18 . The disease typically resolves spontaneously and does not require treatment, and relapse is unusual18 . Adult blaschkitis is a relapsing, linear papulovesicular inflammatory dermatitis that also manifests along the lines of Blaschko 8,17,19 . Alternatively known as acquired relapsing self-healing blaschkitis, adult blaschkitis was first described in 1990 by Grosshans and Marot as a self-limiting eruption of papules, vesicles, and plaques, usually with accompanying pruritus20 . The linear eruptions may be narrow but are
Blaschkoid dermatitis often broad bands, distributed unilaterally or bilaterally along multiple lines of Blaschko, most commonly occurring on the trunk 17,21 . Typically, adult blaschkitis is seen in middle-aged patients with an average age of onset between 40–50 years 17 . Resolution characteristically occurs without treatment, usually within several months, but recurrences are seen in the majority of cases3,18 . Although the timing of presentation and clinical features are often sufficient to make a presumed diagnosis of an acquired linear dermatitis, on occasion, microscopic examination is helpful in securing an accurate diagnosis. Under the microscope, biopsies of lichen striatus classically demonstrate a lichenoid and interface inflammatory infiltrate that extends into the deep dermis to involve the eccrine glands. However, several case series have noted that these features are not present in all cases. Gianotti and colleagues noted peri-adnexal inflammation in only 15 of 22 ‘classic’ cases of pediatric lichen striatus22 , while Zhang and McNutt saw peri-eccrine lymphocytes in 22 of 37 cases of lichen striatus23 , and both groups not infrequently observed mild spongiosis in the biopsies. In contrast, the classic histopathologic pattern seen in adult blaschkitis is a purely spongiotic dermatitis 17,18,20 . Perhaps not unsurprisingly, the lines between these classically distinct categories of ‘childhood-lichenoid linear dermatitis’ and ‘adult- spongiotic linear dermatitis’ are not always respected, and cases of pediatric blaschkitis and adult lichen striatus are reported18 . Additionally, an interface dermatitis without peri-eccrine inflammation as a histopathologic pattern in a classic clinical case of adult blaschkitis has been described 21 . While some authors justify a separation of these entities 18 , others have argued that differences within and between individuals, as well as the time of biopsy, may be enough to account for the variations in clinical and histopathologic features, asserting that blaschkitis and lichen striatus may be the same disease entity3,24 . Regardless of nomenclature, there has been acknowledgement that distinction between the two entities may be somewhat arbitrary and that lichen striatus and adult blaschkitis may represent different points on a spectrum of disease, despite well described clinical and microscopic differences 3,18 . In this case, biopsy of this adult patient with a linear eruption revealed an interface dermatitis with features similar to that seen in erythema
multiforme. Given the clinical and histopathologic findings, it is felt that this case could be interpreted in one of several ways: either as adult blaschkitis or lichen striatus with unusual, non-classic microscopic features, or as a rare and atypical linear distribution of erythema multiforme or other interface dermatitis. To date, only one case report has noted a linear manifestation of erythema multiforme, which was interpreted as such in part because of an associated concurrent herpes simplex virus (HSV) infection 8 . In our case, based on an inability to document antecedent HSV infection or other inciting factor linked to erythema multiforme, this possibility was less favored. As the patient’s initial clinical presentation and early course (including truncal involvement, the patient’s age, and the associated pruritus) followed that of adult blaschkitis, the diagnosis reflected a preference for an unusual pathologic pattern of this entity. Additional clinical features of her disease (the relatively narrow bands of inflammation, involvement of the extremities) and her subsequent clinical course of a persistent process without rapid resolution and relapse suggest that her disease might equally be classified as adult lichen striatus without peri-eccrine inflammation. The overlapping clinical and histopathologic features in this case add to the argument that these entities may be different presentations of the same disease. As linear dermatoses may often be diagnosed on clinical grounds alone, we suspect that the microscopic presentation we report here may be relatively underrepresented in the literature, particularly in the adult population. To our knowledge, our case would be only the second report of adult blaschkitis to demonstrate the histopathology of an interface dermatitis without eccrine gland involvement, although we acknowledge that our case shares overlap with some of the cases described as adult lichen straitus 18 . This case highlights the importance of careful clinicopathologic correlation before arriving at a final diagnosis and adds support to the complex relationship between the entities of blaschkitis and lichen striatus. This case further expands the histopathologic features that may be seen in acquired linear dermatoses in adult patients and strengthens the argument that a spectrum exists regarding the clinical presentation and the microscopic findings in this unusual type of cutaneous disease.
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Johnson et al. References 1. Litvinov IV, Jafarian F. Images in clinical medicine. Lichen striatus and lines of Blaschko. N Engl J Med 2012; 367: 2427. 2. Duran-McKinster C, Moises C, Rodriguez-Jurado R, et al. Streptococcal exanthem in a blaschkolinear pattern: clinical evidence for genetic mosaicism in hypomelanosis of ito. Pediatr Dermatol 2002; 19: 423. 3. Muller CS, Schmaltz R, Vogt T, et al. Lichen striatus and blaschkitis: reappraisal of the concept of blaschkolinear dermatoses. Br J Dermatol 2011; 164: 257. 4. Coskun B, Saral Y, Ozturk P, et al. Calcium acetate-induced linear fixed drug eruption. Dermatology 2005; 210: 244. 5. Kawachi Y, Taguchi S, Fujisawa Y, et al. Linear childhood discoid lupus erythematosus following the lines of Blaschko: successfully treated with topical tacrolimus. Pediatr Dermatol 2011; 28: 205. 6. Li W, Man XY. Linear psoriasis. CMAJ 2012; 184: 789. 7. Hladik F, Jurecka W, Hayek B, et al. Atopic dermatitis with increased severity along a line of Blaschko. J Am Acad Dermatol 2005; 53(Suppl 1): S221. 8. Micalizzi C, Farris A. Erythema multiforme along Blaschko’s lines. J Eur Acad Dermatol Venereol 2000; 14: 203.
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9. Kikuchi A, Okamoto S, Takahashi S, et al. Linear chronic cutaneous graft-versus-host disease. J Am Acad Dermatol 1997; 37: 1004. 10. Brinca A, Santiago F, Serra D, et al. Linear psoriasis - a case report. Case Rep Dermatol 2011; 3: 8. 11. Li H, Wiederkehr M, Rao B, et al. Peculiar unilateral fixed drug eruption of the breast. Int J Dermatol 2002; 41: 96. 12. Ozkaya-Bayazit E, Baykal C. Trimethoprim-induced linear fixed drug eruption. Br J Dermatol 1997; 137: 1028. 13. Sigal-Nahum M, Konqui A, Gaulier A, et al. Linear fixed drug eruption. Br J Dermatol 1988; 118: 849. 14. Taieb A. Linear atopic dermatitis (‘naevus atopicus’): a pathogenetic clue? Br J Dermatol 1994; 131: 134. 15. Turner RJ, Dahl MG, Shuster S, et al. Mosaic atopic eczema cured by autotransplantation? Lancet 1998; 352: 961. 16. Aiyama A, Muro Y, Sugiura K, et al. Extraordinarily long linear cutaneous lupus erythematosus along the lines of Blaschko. Dermatol Online J 2013; 19: 18960.
17. Grosshans EM. Acquired blaschkolinear dermatoses. Am J Med Genet 1999; 85: 334. 18. Keegan BR, Kamino H, Fangman W, et al. “Pediatric blaschkitis”: expanding the spectrum of childhood acquired Blaschko-linear dermatoses. Pediatr Dermatol 2007; 24: 621. 19. Betti R, Vergani R, Gualandri L, et al. Acquired self-healing Blaschko dermatitis in an adult. Australas J Dermatol 1998; 39: 271. 20. Grosshans E, Marot L. Blaschkitis in adults. Ann Dermatol Venereol 1990; 117: 9. 21. Han SH, Song HJ, Hong WK, et al. A case of adult blaschkitis with features of interface dermatitis. Br J Dermatol 2008; 159: 247. 22. Gianotti R, Restano L, Grimalt R, et al. Lichen striatus--a chameleon: an histopathological and immunohistological study of forty-one cases. J Cutan Pathol 1995; 22: 18. 23. Zhang Y, McNutt NS. Lichen striatus. Histological, immunohistochemical, and ultrastructural study of 37 cases. J Cutan Pathol 2001; 28: 65. 24. Hofer T. Lichen striatus in adults or ’adult blaschkitis’?. There is no need for a new naming. Dermatology 2003; 207: 89.
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Journal of Cutaneous Pathology
Interface dermatitis along Blaschko’s lines Linear dermatoses are fascinating entities that likely reflect embryologically derived cutaneous mosaicism, even when they occur after childhood. Adult blaschkitis is a rare, relapsing inflammatory dermatitis that most often presents in middle age. It presents clinically as a pruritic eruption of linear papules, vesicles and plaques, and is most commonly found to have features of spongiotic dermatitis on pathology. However, the clinical and histopathologic presentation of lichen striatus in adults may be similar to those of adult blaschkitis. A case in which ‘blaschkitis’ was suspected clinically is presented, in which the biopsy showed non-characteristic microscopic features resembling erythema multiforme – a finding rarely reported in the literature to date. We present this case and a brief review of the most commonly acquired linear eruptions following Blaschko’s lines with the goal of expanding the histopathologic findings that may be encountered in adult blaschkitis. Moreover, the clinical and histopathologic overlap between the entities of blaschkitis and lichen striatus is explored, acknowledging that these entities may exist on a clinicopathologic spectrum. In the diagnosis of linear eruptions, clinicopathologic correlation is important for arriving at an accurate final diagnosis. Keywords: blaschkitis, lichen striatus, linear, interface, spongiotic Johnson M, Walker D, Galloway W, Gardner JM, Shalin SC. Interface dermatitis along Blaschko’s lines. J Cutan Pathol 2014; 41: 950–954. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Linear eruptions are an intriguing group of diseases and can be dermatomal or Blaschkoid in distribution. A dermatome represents an area of skin that is innervated by a particular spinal nerve (with herpes zoster representing the prototypic cutaneous disease expressed in a dermatomal fashion), while Blaschko’s lines are thought to represent migration pathways taken by epidermal cells during embryogenesis and fetal development. The diseases expressed along these invisible lines of Blaschko are thought to reflect cutaneous mosaicism, with epidermal and dermal cells within that line expressing a common, post-zygotic genetic alteration1 – 3 .
950
Mariah Johnson1 , Daniel Walker2 , William Galloway3 , Jerad M. Gardner2,4 and Sara C. Shalin2,4 1
Department of Dermatology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA , 2 Department of Dermatology, University of Arkansas for Medical Sciences, Little Rock, AR, USA , 3 Russellville Dermatology Clinic, Russellville, AR, USA , and 4 Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
Sara C. Shalin, MD, PhD Assistant Professor, Department of Pathology, University of Arkansas for Medical Sciences, 4301W. Markham Street, Mail Slot # 517, Little Rock, AR 72205, USA Tel: 501-686-8007 Fax: 0501-526-4647 e-mail: [email protected] Accepted for publication July 20, 2014
Report of a Patient A 47-year-old white woman presented to a dermatologist with a 2-month history of a unilateral linear rash occurring along Blaschko lines. Her medical history was notable for depression and infrequent outbreaks of herpes simplex labialis, although she had not experienced an outbreak temporally related to her presenting dermatologic complaint. The rash first appeared as red-brown papules, initially located along the abdomen, which coalesced into linear plaques. She later developed similar linear plaques along her foot, ankle, axilla, and arm, extending to the fingertips (Fig. 1). The lesions were pruritic
Blaschkoid dermatitis
Fig. 1. Unilateral, narrow, linear, red-brown papules and plaques distributed along Blaschko lines in a middle-aged white woman.
but otherwise asymptomatic. Her only medication included citalopram, which she had been taking for many years prior to this rash formation. Direct fluorescent antibody testing for varicella, performed by her primary care physician, was negative, prompting referral to a dermatologist. Upon presentation, the dermatologist clinically considered adult-onset nevus unius lateris versus an acquired linear dermatitis and performed a biopsy for confirmation. She was treated with a potent topical corticosteroid to help relieve pruritus, which improved this symptom and also lessened the erythema. Subsequent to the biopsy, she was presented at the local Dermatology Grand Rounds, where her clinical and histopathologic findings were discussed. The clinical impression was felt to be most consistent with adult blaschkitis given the patient’s age of onset, truncal involvement and accompanying pruritus. Histopathologic examination of a biopsy obtained from the left flank revealed the presence of interface dermatitis. Numerous apoptotic keratinocytes were seen at all levels within the epidermis, many of them adjacent to infiltrating lymphocytes (Figs. 2 and 3). Within the dermis, there was a mild lymphohistiocytic inflammatory infiltrate with vacuolar interface changes along the dermal–epidermal junction; the eccrine glands were without significant inflammation (Fig. 4). The histopathologic features were most suggestive of an interface dermatitis such as erythema multiforme, but, given the clinical presentation and the lack of triggering factors for either erythema multiforme or a linear fixed drug eruption (FDE), the findings were
Fig. 2. Scanning magnification reveals a punch biopsy with interface dermatitis. The deep reticular dermis is spared of involvement.
Fig. 3. Numerous apoptotic keratinocytes are seen within the epidermis, many of them adjacent to infiltrating lymphocytes. Within the superficial dermis, there is a lymphohistiocytic infiltrate with an interface component.
interpreted as compatible with the clinical impression of adult blaschkitis, albeit one with an unusual microscopic pattern. Approximately 1 year after the patient’s initial presentation, she reported persistence of the linear eruption, with periodic flares of pruritus, which she treated with topical corticosteroids.
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Johnson et al.
Fig. 4. The eccrine glands are without significant inflammation.
Discussion Linear dermatoses represent a fascinating category of cutaneous disorders. Linear eruptions along the lines of Blaschko, in particular, may be congenital or acquired. Incontinentia pigmenti and variants of epidermal nevi (inflammatory linear verrucous epidermal nevus, linear porokeratosis, and linear nevus sebaceous) are examples of congenital blaschkoid lesions, which most commonly manifest at birth or within the first several years of life. Acquired linear eruptions in a blaschkoid distribution may be common dermatoses presenting in an unusual, linear distribution. For example, psoriasis, atopic dermatitis, lupus erythematosus, FDEs, graft-versus-host disease and even erythema multiforme all have been reported occurring in along Blaschko lines4 – 9 . Other entities, namely lichen striatus and adult blaschkitis, routinely present in a linear pattern. Psoriasis is a chronic, immune-mediated, proliferative skin disorder, which clinically presents as scaly erythematous plaques and affects about 2% of the population6 . Linear psoriasis is a rare subtype of psoriasis that is distributed along lines of Blaschko. Characterized microscopically by acanthosis, confluent parakeratosis, hypogranulosis, and intraepidermal neutrophils, these lesions are usually asymptomatic to slightly pruritic and respond to conventional antipsoriatic treatments6,10 . FDE typically presents as a solitary erythematous, oval patch on the lips, trunk, upper
952
extremities, or penis and develops within hours of exposure to an inciting agent. Lesions resolve within 7–10 days but characteristically recur in the same location when the patient is reintroduced to the causative drug 4,11 . A lichenoid dermatitis with orthokeratosis, mixed dermal inflammatory infiltrate, and marked pigment incontinence are seen upon histopathologic examination. Very few cases of linear FDE have been reported; these documented cases include reactions to naproxen11 , trimethoprim12 , cephazolin13 and calcium-acetate4 . Atopic dermatitis may rarely present as a linear erythematous, papulovesicular eruption along lines of Blaschko in predisposed atopic patients, with histopathologic examination showing a spongiotic dermatitis 7 . To date, only three cases have been documented, including an 8-year-old girl with involvement of the left arm 14 , an 18-year-old female with involvement of her right leg15 and a 36-year-old man with involvement of the left leg7 . Linear cutaneous lupus erythematosus (LCLE) is a rare subtype of cutaneous lupus erythematosus which usually develops on the face and is most commonly seen in pediatric patients 5,16 . However, cases of LCLE occurring in adults and manifesting along the trunk and extremities have also been reported 16 . Biopsies of discoid lupus lesions reveal basal vacuolar change and interface dermatitis, with epidermal atrophy, follicular plugging, dermal mucin deposition and a periappendageal lymphocytic infiltrate. Of inflammatory dermatoses that routinely present in a linear fashion, lichen striatus and adult blaschkitis are the best described. Lichen striatus is a cutaneous disease of childhood, presenting as a self-limited, usually asymptomatic, linear rash with an average age of onset between 3 and 4 years 17,18 . Lichen striatus usually appears as an eruption of small erythematous papules that coalesce into a solitary, usually unilateral, narrow band on an extremity over the course of several days to weeks 17,18 . The disease typically resolves spontaneously and does not require treatment, and relapse is unusual18 . Adult blaschkitis is a relapsing, linear papulovesicular inflammatory dermatitis that also manifests along the lines of Blaschko 8,17,19 . Alternatively known as acquired relapsing self-healing blaschkitis, adult blaschkitis was first described in 1990 by Grosshans and Marot as a self-limiting eruption of papules, vesicles, and plaques, usually with accompanying pruritus20 . The linear eruptions may be narrow but are
Blaschkoid dermatitis often broad bands, distributed unilaterally or bilaterally along multiple lines of Blaschko, most commonly occurring on the trunk 17,21 . Typically, adult blaschkitis is seen in middle-aged patients with an average age of onset between 40–50 years 17 . Resolution characteristically occurs without treatment, usually within several months, but recurrences are seen in the majority of cases3,18 . Although the timing of presentation and clinical features are often sufficient to make a presumed diagnosis of an acquired linear dermatitis, on occasion, microscopic examination is helpful in securing an accurate diagnosis. Under the microscope, biopsies of lichen striatus classically demonstrate a lichenoid and interface inflammatory infiltrate that extends into the deep dermis to involve the eccrine glands. However, several case series have noted that these features are not present in all cases. Gianotti and colleagues noted peri-adnexal inflammation in only 15 of 22 ‘classic’ cases of pediatric lichen striatus22 , while Zhang and McNutt saw peri-eccrine lymphocytes in 22 of 37 cases of lichen striatus23 , and both groups not infrequently observed mild spongiosis in the biopsies. In contrast, the classic histopathologic pattern seen in adult blaschkitis is a purely spongiotic dermatitis 17,18,20 . Perhaps not unsurprisingly, the lines between these classically distinct categories of ‘childhood-lichenoid linear dermatitis’ and ‘adult- spongiotic linear dermatitis’ are not always respected, and cases of pediatric blaschkitis and adult lichen striatus are reported18 . Additionally, an interface dermatitis without peri-eccrine inflammation as a histopathologic pattern in a classic clinical case of adult blaschkitis has been described 21 . While some authors justify a separation of these entities 18 , others have argued that differences within and between individuals, as well as the time of biopsy, may be enough to account for the variations in clinical and histopathologic features, asserting that blaschkitis and lichen striatus may be the same disease entity3,24 . Regardless of nomenclature, there has been acknowledgement that distinction between the two entities may be somewhat arbitrary and that lichen striatus and adult blaschkitis may represent different points on a spectrum of disease, despite well described clinical and microscopic differences 3,18 . In this case, biopsy of this adult patient with a linear eruption revealed an interface dermatitis with features similar to that seen in erythema
multiforme. Given the clinical and histopathologic findings, it is felt that this case could be interpreted in one of several ways: either as adult blaschkitis or lichen striatus with unusual, non-classic microscopic features, or as a rare and atypical linear distribution of erythema multiforme or other interface dermatitis. To date, only one case report has noted a linear manifestation of erythema multiforme, which was interpreted as such in part because of an associated concurrent herpes simplex virus (HSV) infection 8 . In our case, based on an inability to document antecedent HSV infection or other inciting factor linked to erythema multiforme, this possibility was less favored. As the patient’s initial clinical presentation and early course (including truncal involvement, the patient’s age, and the associated pruritus) followed that of adult blaschkitis, the diagnosis reflected a preference for an unusual pathologic pattern of this entity. Additional clinical features of her disease (the relatively narrow bands of inflammation, involvement of the extremities) and her subsequent clinical course of a persistent process without rapid resolution and relapse suggest that her disease might equally be classified as adult lichen striatus without peri-eccrine inflammation. The overlapping clinical and histopathologic features in this case add to the argument that these entities may be different presentations of the same disease. As linear dermatoses may often be diagnosed on clinical grounds alone, we suspect that the microscopic presentation we report here may be relatively underrepresented in the literature, particularly in the adult population. To our knowledge, our case would be only the second report of adult blaschkitis to demonstrate the histopathology of an interface dermatitis without eccrine gland involvement, although we acknowledge that our case shares overlap with some of the cases described as adult lichen straitus 18 . This case highlights the importance of careful clinicopathologic correlation before arriving at a final diagnosis and adds support to the complex relationship between the entities of blaschkitis and lichen striatus. This case further expands the histopathologic features that may be seen in acquired linear dermatoses in adult patients and strengthens the argument that a spectrum exists regarding the clinical presentation and the microscopic findings in this unusual type of cutaneous disease.
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Johnson et al. References 1. Litvinov IV, Jafarian F. Images in clinical medicine. Lichen striatus and lines of Blaschko. N Engl J Med 2012; 367: 2427. 2. Duran-McKinster C, Moises C, Rodriguez-Jurado R, et al. Streptococcal exanthem in a blaschkolinear pattern: clinical evidence for genetic mosaicism in hypomelanosis of ito. Pediatr Dermatol 2002; 19: 423. 3. Muller CS, Schmaltz R, Vogt T, et al. Lichen striatus and blaschkitis: reappraisal of the concept of blaschkolinear dermatoses. Br J Dermatol 2011; 164: 257. 4. Coskun B, Saral Y, Ozturk P, et al. Calcium acetate-induced linear fixed drug eruption. Dermatology 2005; 210: 244. 5. Kawachi Y, Taguchi S, Fujisawa Y, et al. Linear childhood discoid lupus erythematosus following the lines of Blaschko: successfully treated with topical tacrolimus. Pediatr Dermatol 2011; 28: 205. 6. Li W, Man XY. Linear psoriasis. CMAJ 2012; 184: 789. 7. Hladik F, Jurecka W, Hayek B, et al. Atopic dermatitis with increased severity along a line of Blaschko. J Am Acad Dermatol 2005; 53(Suppl 1): S221. 8. Micalizzi C, Farris A. Erythema multiforme along Blaschko’s lines. J Eur Acad Dermatol Venereol 2000; 14: 203.
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