EXTRAORDINARY CASE REPORT
Solitary Fibrous Tumor With Myxoid Stromal Change Jin Yong Lee, MD,* So Eun Park, MD,* Soo Jung Shin, MD,* Chul Woo Kim, MD,* Sang Seok Kim, MD,* and Kwang Ho Kim, MD, PhD†
Abstract: We report the case of a 46-year-old Korean woman who presented with a 5-month history of a hyperkeratotic plaque on the left palm. On examination, the plaque showed an annular pattern with an umbilicated central nodule and a peripheral palisading induration, which had a verrucous surface. After surgical resection, histopathologic analysis revealed that the tumor was composed of haphazardly arranged spindle cells and displayed a predominantly myxoid appearance in the stroma. The tumor cells were positive for CD34 and bcl-2, but negative for smooth muscle actin and S-100. The clinical manifestation and histopathologic findings were most consistent with a diagnosis of solitary fibrous tumor with myxoid stromal change. There was no evidence of recurrence or metastasis during the 8-month follow-up period. This case highlights the importance of an accurate diagnosis of solitary fibrous tumors, which may have extensive myxoid stromal change, hence mimicking other myxoid-type spindle cell tumors. Key Words: CD34, myxoid stromal change, solitary fibrous tumor, spindle cell tumor (Am J Dermatopathol 2015;37:570–573)
INTRODUCTION
Solitary fibrous tumors (SFTs) are rare mesenchymal tumors, presenting as asymptomatic nodules or masses that usually arise in the pleura but can also occur in extrapleural areas, including the nasal cavity, orbit, retroperitoneum, pelvis, liver, bladder, soft tissue, and skin.1–6 SFTs may occur across a wide age range, but many patients are middle-aged, and there is no sex predilection.7 Most SFTs appear benign, with a low recurrence rate of 10%–15%, although some of the atypical histological features of the tumors, including an infiltrative growth pattern, dense cellularity, pleomorphism with atypia, and a high mitotic rate, can be associated with aggressive or metastatic behavior.4 Since first reported by de Saint Aubain Somerhausen et al,8 very few additional cases of a myxoid SFT, a relatively rare morphological variant, have been reported. Here, we describe a case of a SFT with myxoid stromal change, an unusual From the *Department of Dermatology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea; and †Department of Dermatology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea. The authors declare no conflicts of interest. Reprints: Kwang Ho Kim, MD, PhD, Department of Dermatology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 896, Pyeongchon-dong, Dongan-gu, Anyang, Gyeonggi-do, 431-070, Korea (e-mail: [email protected]). Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.
570
| www.amjdermatopathology.com
condition in the skin. This case could contribute to the understanding of the histologic and clinical features of myxoid SFTs, which have not been well defined to date because of their rarity.
CASE REPORT A 46-year-old Korean woman presented with a hyperkeratotic, verrucous, slow-growing plaque on her left palm that had been present for 5 months. The patient used to experience mild pain with slight touch in everyday life and reported no history of trauma at the site. She was not taking any medications and was otherwise healthy. Cutaneous examination revealed a 1.0 · 1.0 cm plaque composed of a central nodule with umbilication and peripheral palisading induration, presenting with an annular pattern (Fig. 1). On palpation, a tender scaly nodule with umbilication was noted in the center of the plaque, whereas hard, stiff, dry, scaly, verrucous palisading induration was noted at the periphery. The findings on examination of other organ systems were unremarkable, and the lesion was clinically suspected to be a verruca. For diagnostic evaluation, punch biopsy and ultrasonography were performed at the site of the left palm. Ultrasonography showed relatively well-defined 1.0-cm ovoid hypoechoic lesion in the subcutaneous fat layer (Fig. 2). Punch biopsy of the lesion showed a portion of a circumscribed dermal nodule composed of spindle cells with peripheral myxoid stromal change. Thereafter, the tumor was completely excised under local anesthesia to facilitate an accurate diagnosis and appropriate management. Histopathological analysis of the excised lesion identified a tumor that was characterized by proliferation of bland spindle cells arranged haphazardly in a loose myxoid stroma (Fig. 3). The spindle
FIGURE 1. A skin-colored hyperkeratotic, painful, round, verrucous plaque, 1.0 · 1.0 cm in size, was observed on the patient’s left palm. The plaque was composed of a central nodule with umbilication and peripheral palisading induration, with an annular pattern. Am J Dermatopathol Volume 37, Number 7, July 2015
Am J Dermatopathol Volume 37, Number 7, July 2015
Myxoid Solitary Fibrous Tumor at the periphery of the tumor (Fig. 4). On immunohistochemistry, the tumor cells were positive for CD34 and bcl-2, but negative for S-100 protein and smooth muscle actin. Extensive myxoid stromal change was confirmed by Alcian blue staining. The densely interspersed collagen bundles showed a positive reaction on Masson’s trichrome staining (Fig. 5). Accordingly, a SFT with extensive myxoid stromal change was diagnosed. The patient did not experience any complications during the 8-month follow-up, although a longer follow-up period may be required to monitor recurrence and metastasis.
DISCUSSION FIGURE 2. An ultrasound image shows a well-circumscribed, ovoid, hypoechoic mass, 1.0 cm in diameter, in the subcutaneous fat layer. cells formed fascicles of variable lengths with hypercellular and hypocellular areas. The overlying epidermis showed hyperkeratosis and epidermal hyperplasia. No atypical mitoses were observed. Several irregularly shaped vascular structures with erythrocytes were present
FIGURE 3. An SFT appears as a circumscribed dermal nodule composed of bland spindle cells with extensive myxoid stromal change in the background. Upper part (A) and lower part (B) (hematoxylin and eosin, ·20). Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
SFT is a relatively uncommon mesenchymal neoplasm that usually involves the pleura, but also occurs in numerous extrapleural locations.1–6 Although initially believed to be of mesothelial origin, SFT is now recognized as being of mesenchymal origin, arising from primitive fibroblast-like cells in connective tissue.9 Myxoid SFT, a SFT variant, has been described as a solid mass with white- to skin-colored, firm, fibrous cut surfaces accompanied by softer areas of gelatinous-appearing myxoid stromal change in $50% of the tumor.10 However, myxoid SFT is a rare variant or subgroup of the already uncommon SFT, and therefore, only a few features associated with this tumor have been described.11 A common histopathologic finding of SFTs is a “patternless pattern,” implying that the tumor does not have a single appearance that can be considered characteristic. In fact, several typical growth patterns including storiform, herringbone, fascicular, angiofibromatous, and hemangiopericytoma-like arrangements have been previously reported.4,6 Architecturally, the tumors have both hypercellular (tumor cell–rich) and hypocellular (collagen-rich) areas and are composed of bland spindle cells with pale vesicular nuclei, inconspicuous nucleoli, and indistinct cell borders. The histopathologic features of myxoid SFT are relatively nonspecific and include the presence of an abundant, pale, myxoid matrix, which may appear in focal areas, but extensive involvement is not common. The monoclonal antibody CD34, a transmembrane cell surface glycoprotein, originally described on hematopoietic stem cells, endothelial cells, and fibroblasts, is widely considered a diagnostic marker for SFT.2,12 In addition, the tumor cells express CD99, bcl-2, and, focally, factor XIIIa but are negative for smooth muscle, neural, and epithelial markers. SFT can usually be distinguished from other spindle cell tumors such as dermatofibroma, dermatofibrosarcoma protuberans, low-grade fibromyxoid sarcoma, myxofibrosarcoma, spindle cell lipoma, leiomyoma/leiomyosarcoma, and malignant peripheral nerve sheath tumor on the basis of characteristic cutaneous patterns (Table 1).13 However, its diagnosis is sometimes potentially challenging because of the histologic variability. Judicious application of immunohistochemistry for markers such as CD34, CD99, and bcl-2 can be helpful in arriving at the correct diagnosis. Further imaging studies, including ultrasonography, magnetic resonance imaging, and positron emission tomography–computed tomography, can also have a role in differentiating benign and malignant SFTs and may additionally prove useful in distinguishing SFTs from other spindle cell tumors and assessing the extent of involvement of adjacent skin structures.7 Specifically, www.amjdermatopathology.com |
571
Lee et al
Am J Dermatopathol Volume 37, Number 7, July 2015
FIGURE 4. The tumor shows proliferation of bland spindle cells in alternating hypercellular and hypocellular areas, with interspersed collagen bundles (A). Irregularly shaped, thin-walled, vascular structures are seen at the periphery on low-power magnification (B). Individual tumor cells with plump, spindle-shaped nuclei are embedded in a myxoid stroma, and no pleomorphism or atypia is noted (C). Prominent myxoid stromal change with a loose fascicular growth pattern is seen (D). [hematoxylin and eosin, ·40 (A, B), ·100 (C, D)].
malignant spindle cell tumors should be ruled out in the presence of increased cellularity, pleomorphism, or atypical mitoses. In patients with SFTs, a tumor size of .10 cm, an infiltrative growth pattern, dense cellularity, nuclear pleomorphism, and frequent mitoses (.4 per 10 high-power fields) are associated
with malignancy.4,14 Most extrapleural SFTs behave rather innocuously, but approximately 10%–15% show local recurrences, and repeated recurrence is sometimes noted. Rarely, SFTs may metastasize to distant sites as well. Therefore, in most cases, complete or wide excision is recommended to treat SFTs.
FIGURE 5. Immunohistochemically, the tumor cells show strong positivity for CD34 (A) and bcl-2 (B). The myxoid stroma was diffusely reactive on Alcian blue staining (C) and the interspersed collagen bundles were reactive on Masson’s trichrome (MT) staining (D). [CD34, ·200 (A); bcl-2, ·200 (B); Alcian blue, ·200 (C); MT, ·200 (D)].
572
| www.amjdermatopathology.com
Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
Am J Dermatopathol Volume 37, Number 7, July 2015
Myxoid Solitary Fibrous Tumor
TABLE 1. Spindle Cell Tumors That Mimic Myxoid Solitary Fibrous Tumors Disease Entity Myxoid SFT
Clinical Features
Histopathologic Features
Usually arising in the pleura, but also at extrapleural sites
Immunohistochemistry
Patternless pattern; alternating hypercellular and hypocellular areas; abundant pale myxoid matrix Dermatofibroma Predominantly occurring on the Epidermal hyperplasia; separation by a extremities and trunk but rarely on the grenz zone; composed of fibroblasthands and feet like spindle cells, histiocytes, and blood vessels Dermatofibrosarcoma Most common on the trunk and proximal Diffuse infiltration of densely packed protuberans extremities; sometimes accompanied spindle cells; storiform, honeycomb, or by ulceration fascicular pattern; myxoid areas may occur, especially in recurrent lesions Low-grade fibromyxoid Predilection for the proximal extremities Whorled or swirling growth pattern; sarcoma and trunk alternating fibrous and myxoid stroma (biphasic pattern); cytologic atypia and small dark nuclei Myxofibrosarcoma Usually arising in deep soft tissues; Multinodular growth with fibrous septa; slowly enlarging painless mass in the pseudolipoblasts with mucin extremities of the elderly Spindle cell lipoma Slowly growing subcutaneous tumor; Mature adipocytes and uniform spindle particularly common on the shoulder cells within a mucinous matrix; girdle, nape, and upper back; more scattered mast cells common in men Leiomyoma/leiomyosarcoma Often painful; most common on the Eosinophilic cytoplasm with blunt-ended shoulder or upper arm cigar-shaped nuclei; long rather than short fascicles Malignant peripheral nerve Association with neurofibromatosis Wavy or buckled nuclei; perivascular sheath tumor condensation
CD34 (+), CD99 (+), factor XIIIa (6), SMA (2), S-100 (2), EMA (6), desmin (2), bcl-2 (+) CD34 (6), factor XIIIa (+), SMA (6), S-100 (2), EMA (2), desmin (2), bcl-2 (2) CD34 (+), factor XIIIa (6), vimentin (+), SMA (6), S-100 (2), EMA (2), desmin (2), bcl-2 (6) Vimentin (+), CD34 (6), EMA (6), desmin (2)
Vimentin (+), CD 68 (+), CD34 (2), S-100 (2) CD34 (+), CD99 (+), vimentin (+), S-100 (2), SMA (2)
SMA (+), desmin (+), CD34 (2), bcl-2 (2), MT (+) S-100 (+), bcl-2 (6), SMA (6)
SMA, smooth muscle actin; EMA, epithelial membrane antigen; MT, Masson’s trichrome.
The biological behavior of myxoid SFTs has not been described in detail and is still being investigated because of the tumors’ rare incidence. Lau et al14 reported that myxoid SFTs are associated with an indolent clinical course and low potential for recurrence and metastasis, on the basis of their experience with 3 cases. The 3 new cases described by Dantey and Cooper10 also demonstrated a favorable prognosis. None of these cases showed pathologic atypia, recurrence, or metastasis during a follow-up period of 3–87 months. According to the literature review conducted by Lau et al,14 8 studies with a total of 14 cases of myxoid SFT have been reported worldwide. Taken together with the previously mentioned cases, our case provides additional support for the tendency of myxoid SFTs to have a benign or favorable course. Focal myxoid stromal change is a well-recognized feature of SFTs. However, predominant or extensive myxoid appearances have rarely been reported in the recent dermatologic literature. To our knowledge, this is the first reported case of presentation on the palm. Recognition of this uncommon morphologic subset of SFT is important because of possible confusion, particularly in cases of small biopsy specimens, with a variety of myxoid spindle cell tumors with varying biologic potential. Thus, we report this case of a rare occurrence of SFT with myxoid stromal change in the skin, which initially suggested the diagnosis of verruca, and highlight the fact that SFT should be considered in the differential diagnosis of various superficial spindle cell tumors accompanied by myxoid change. Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
REFERENCES
1. Hardisson D, Cuevas-Santos J, Contreras F. Solitary fibrous tumor of the skin. J Am Acad Dermatol. 2002;46:S37–S40. 2. Chan JK. Solitary fibrous tumour—everywhere, and a diagnosis in vogue. Histopathology. 1997;31:568–576. 3. Gold JS, Antonescu CR, Hajdu C, et al. Clinicopathologic correlates of solitary fibrous tumors. Cancer. 2002;94:1057–1068. 4. Erdag G, Qureshi HS, Patterson JW, et al. Solitary fibrous tumors of the skin: a clinicopathologic study of 10 cases and review of the literature. J Cutan Pathol. 2007;34:844–850. 5. Morimitsu Y, Nakajima M, Hisaoka M, et al. Extrapleural solitary fibrous tumor: clinicopathologic study of 17 cases and molecular analysis of the p53 pathway. APMIS. 2000;108:617–625. 6. Soldano AC, Meehan SA. Cutaneous solitary fibrous tumor: a report of 2 cases and review of the literature. Am J Dermatopathol. 2008;30:54–58. 7. Musyoki FN, Nahal A, Powell TI. Solitary fibrous tumor: an update on the spectrum of extrapleural manifestations. Skeletal Radiol. 2012;41:5–13. 8. de Saint Aubain Somerhausen N, Rubin BP, Fletcher CD. Myxoid solitary fibrous tumor: a study of seven cases with emphasis on differential diagnosis. Mod Pathol. 1999;12:463–471. 9. Morgan MB, Smoller BR. Solitary fibrous tumors are immunophenotypically distinct from mesothelioma(s). J Cutan Pathol. 2000;27:451–454. 10. Dantey K, Cooper K. Myxoid solitary fibrous tumor: a study of three cases. Int J Surg Pathol. 2013;21:358–362. 11. Yap T, Hamzah L, Oshowo A, et al. Myxoid solitary fibrous tumour of the ischiorectal fossa. Eur J Surg Oncol. 2003;29:98–100. 12. Yilmaz C, Kabatas S, Ozen OI, et al. Solitary fibrous tumor. J Clin Neurosci. 2009;16:1578–1581. 13. Wood L, Fountaine TJ, Rosamilia L, et al. Cutaneous CD34+ spindle cell neoplasms: histopathologic features distinguish spindle cell lipoma, solitary fibrous tumor, and dermatofibrosarcoma protuberans. Am J Dermatopathol. 2010;32:764–768. 14. Lau SK, Weiss LM, Chu PG. Myxoid solitary fibrous tumor: a clinicopathologic study of three cases. Virchows Arch. 2009;454:189–194.
www.amjdermatopathology.com |
573
Solitary Fibrous Tumor With Myxoid Stromal Change Jin Yong Lee, MD,* So Eun Park, MD,* Soo Jung Shin, MD,* Chul Woo Kim, MD,* Sang Seok Kim, MD,* and Kwang Ho Kim, MD, PhD†
Abstract: We report the case of a 46-year-old Korean woman who presented with a 5-month history of a hyperkeratotic plaque on the left palm. On examination, the plaque showed an annular pattern with an umbilicated central nodule and a peripheral palisading induration, which had a verrucous surface. After surgical resection, histopathologic analysis revealed that the tumor was composed of haphazardly arranged spindle cells and displayed a predominantly myxoid appearance in the stroma. The tumor cells were positive for CD34 and bcl-2, but negative for smooth muscle actin and S-100. The clinical manifestation and histopathologic findings were most consistent with a diagnosis of solitary fibrous tumor with myxoid stromal change. There was no evidence of recurrence or metastasis during the 8-month follow-up period. This case highlights the importance of an accurate diagnosis of solitary fibrous tumors, which may have extensive myxoid stromal change, hence mimicking other myxoid-type spindle cell tumors. Key Words: CD34, myxoid stromal change, solitary fibrous tumor, spindle cell tumor (Am J Dermatopathol 2015;37:570–573)
INTRODUCTION
Solitary fibrous tumors (SFTs) are rare mesenchymal tumors, presenting as asymptomatic nodules or masses that usually arise in the pleura but can also occur in extrapleural areas, including the nasal cavity, orbit, retroperitoneum, pelvis, liver, bladder, soft tissue, and skin.1–6 SFTs may occur across a wide age range, but many patients are middle-aged, and there is no sex predilection.7 Most SFTs appear benign, with a low recurrence rate of 10%–15%, although some of the atypical histological features of the tumors, including an infiltrative growth pattern, dense cellularity, pleomorphism with atypia, and a high mitotic rate, can be associated with aggressive or metastatic behavior.4 Since first reported by de Saint Aubain Somerhausen et al,8 very few additional cases of a myxoid SFT, a relatively rare morphological variant, have been reported. Here, we describe a case of a SFT with myxoid stromal change, an unusual From the *Department of Dermatology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea; and †Department of Dermatology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea. The authors declare no conflicts of interest. Reprints: Kwang Ho Kim, MD, PhD, Department of Dermatology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 896, Pyeongchon-dong, Dongan-gu, Anyang, Gyeonggi-do, 431-070, Korea (e-mail: [email protected]). Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.
570
| www.amjdermatopathology.com
condition in the skin. This case could contribute to the understanding of the histologic and clinical features of myxoid SFTs, which have not been well defined to date because of their rarity.
CASE REPORT A 46-year-old Korean woman presented with a hyperkeratotic, verrucous, slow-growing plaque on her left palm that had been present for 5 months. The patient used to experience mild pain with slight touch in everyday life and reported no history of trauma at the site. She was not taking any medications and was otherwise healthy. Cutaneous examination revealed a 1.0 · 1.0 cm plaque composed of a central nodule with umbilication and peripheral palisading induration, presenting with an annular pattern (Fig. 1). On palpation, a tender scaly nodule with umbilication was noted in the center of the plaque, whereas hard, stiff, dry, scaly, verrucous palisading induration was noted at the periphery. The findings on examination of other organ systems were unremarkable, and the lesion was clinically suspected to be a verruca. For diagnostic evaluation, punch biopsy and ultrasonography were performed at the site of the left palm. Ultrasonography showed relatively well-defined 1.0-cm ovoid hypoechoic lesion in the subcutaneous fat layer (Fig. 2). Punch biopsy of the lesion showed a portion of a circumscribed dermal nodule composed of spindle cells with peripheral myxoid stromal change. Thereafter, the tumor was completely excised under local anesthesia to facilitate an accurate diagnosis and appropriate management. Histopathological analysis of the excised lesion identified a tumor that was characterized by proliferation of bland spindle cells arranged haphazardly in a loose myxoid stroma (Fig. 3). The spindle
FIGURE 1. A skin-colored hyperkeratotic, painful, round, verrucous plaque, 1.0 · 1.0 cm in size, was observed on the patient’s left palm. The plaque was composed of a central nodule with umbilication and peripheral palisading induration, with an annular pattern. Am J Dermatopathol Volume 37, Number 7, July 2015
Am J Dermatopathol Volume 37, Number 7, July 2015
Myxoid Solitary Fibrous Tumor at the periphery of the tumor (Fig. 4). On immunohistochemistry, the tumor cells were positive for CD34 and bcl-2, but negative for S-100 protein and smooth muscle actin. Extensive myxoid stromal change was confirmed by Alcian blue staining. The densely interspersed collagen bundles showed a positive reaction on Masson’s trichrome staining (Fig. 5). Accordingly, a SFT with extensive myxoid stromal change was diagnosed. The patient did not experience any complications during the 8-month follow-up, although a longer follow-up period may be required to monitor recurrence and metastasis.
DISCUSSION FIGURE 2. An ultrasound image shows a well-circumscribed, ovoid, hypoechoic mass, 1.0 cm in diameter, in the subcutaneous fat layer. cells formed fascicles of variable lengths with hypercellular and hypocellular areas. The overlying epidermis showed hyperkeratosis and epidermal hyperplasia. No atypical mitoses were observed. Several irregularly shaped vascular structures with erythrocytes were present
FIGURE 3. An SFT appears as a circumscribed dermal nodule composed of bland spindle cells with extensive myxoid stromal change in the background. Upper part (A) and lower part (B) (hematoxylin and eosin, ·20). Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
SFT is a relatively uncommon mesenchymal neoplasm that usually involves the pleura, but also occurs in numerous extrapleural locations.1–6 Although initially believed to be of mesothelial origin, SFT is now recognized as being of mesenchymal origin, arising from primitive fibroblast-like cells in connective tissue.9 Myxoid SFT, a SFT variant, has been described as a solid mass with white- to skin-colored, firm, fibrous cut surfaces accompanied by softer areas of gelatinous-appearing myxoid stromal change in $50% of the tumor.10 However, myxoid SFT is a rare variant or subgroup of the already uncommon SFT, and therefore, only a few features associated with this tumor have been described.11 A common histopathologic finding of SFTs is a “patternless pattern,” implying that the tumor does not have a single appearance that can be considered characteristic. In fact, several typical growth patterns including storiform, herringbone, fascicular, angiofibromatous, and hemangiopericytoma-like arrangements have been previously reported.4,6 Architecturally, the tumors have both hypercellular (tumor cell–rich) and hypocellular (collagen-rich) areas and are composed of bland spindle cells with pale vesicular nuclei, inconspicuous nucleoli, and indistinct cell borders. The histopathologic features of myxoid SFT are relatively nonspecific and include the presence of an abundant, pale, myxoid matrix, which may appear in focal areas, but extensive involvement is not common. The monoclonal antibody CD34, a transmembrane cell surface glycoprotein, originally described on hematopoietic stem cells, endothelial cells, and fibroblasts, is widely considered a diagnostic marker for SFT.2,12 In addition, the tumor cells express CD99, bcl-2, and, focally, factor XIIIa but are negative for smooth muscle, neural, and epithelial markers. SFT can usually be distinguished from other spindle cell tumors such as dermatofibroma, dermatofibrosarcoma protuberans, low-grade fibromyxoid sarcoma, myxofibrosarcoma, spindle cell lipoma, leiomyoma/leiomyosarcoma, and malignant peripheral nerve sheath tumor on the basis of characteristic cutaneous patterns (Table 1).13 However, its diagnosis is sometimes potentially challenging because of the histologic variability. Judicious application of immunohistochemistry for markers such as CD34, CD99, and bcl-2 can be helpful in arriving at the correct diagnosis. Further imaging studies, including ultrasonography, magnetic resonance imaging, and positron emission tomography–computed tomography, can also have a role in differentiating benign and malignant SFTs and may additionally prove useful in distinguishing SFTs from other spindle cell tumors and assessing the extent of involvement of adjacent skin structures.7 Specifically, www.amjdermatopathology.com |
571
Lee et al
Am J Dermatopathol Volume 37, Number 7, July 2015
FIGURE 4. The tumor shows proliferation of bland spindle cells in alternating hypercellular and hypocellular areas, with interspersed collagen bundles (A). Irregularly shaped, thin-walled, vascular structures are seen at the periphery on low-power magnification (B). Individual tumor cells with plump, spindle-shaped nuclei are embedded in a myxoid stroma, and no pleomorphism or atypia is noted (C). Prominent myxoid stromal change with a loose fascicular growth pattern is seen (D). [hematoxylin and eosin, ·40 (A, B), ·100 (C, D)].
malignant spindle cell tumors should be ruled out in the presence of increased cellularity, pleomorphism, or atypical mitoses. In patients with SFTs, a tumor size of .10 cm, an infiltrative growth pattern, dense cellularity, nuclear pleomorphism, and frequent mitoses (.4 per 10 high-power fields) are associated
with malignancy.4,14 Most extrapleural SFTs behave rather innocuously, but approximately 10%–15% show local recurrences, and repeated recurrence is sometimes noted. Rarely, SFTs may metastasize to distant sites as well. Therefore, in most cases, complete or wide excision is recommended to treat SFTs.
FIGURE 5. Immunohistochemically, the tumor cells show strong positivity for CD34 (A) and bcl-2 (B). The myxoid stroma was diffusely reactive on Alcian blue staining (C) and the interspersed collagen bundles were reactive on Masson’s trichrome (MT) staining (D). [CD34, ·200 (A); bcl-2, ·200 (B); Alcian blue, ·200 (C); MT, ·200 (D)].
572
| www.amjdermatopathology.com
Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
Am J Dermatopathol Volume 37, Number 7, July 2015
Myxoid Solitary Fibrous Tumor
TABLE 1. Spindle Cell Tumors That Mimic Myxoid Solitary Fibrous Tumors Disease Entity Myxoid SFT
Clinical Features
Histopathologic Features
Usually arising in the pleura, but also at extrapleural sites
Immunohistochemistry
Patternless pattern; alternating hypercellular and hypocellular areas; abundant pale myxoid matrix Dermatofibroma Predominantly occurring on the Epidermal hyperplasia; separation by a extremities and trunk but rarely on the grenz zone; composed of fibroblasthands and feet like spindle cells, histiocytes, and blood vessels Dermatofibrosarcoma Most common on the trunk and proximal Diffuse infiltration of densely packed protuberans extremities; sometimes accompanied spindle cells; storiform, honeycomb, or by ulceration fascicular pattern; myxoid areas may occur, especially in recurrent lesions Low-grade fibromyxoid Predilection for the proximal extremities Whorled or swirling growth pattern; sarcoma and trunk alternating fibrous and myxoid stroma (biphasic pattern); cytologic atypia and small dark nuclei Myxofibrosarcoma Usually arising in deep soft tissues; Multinodular growth with fibrous septa; slowly enlarging painless mass in the pseudolipoblasts with mucin extremities of the elderly Spindle cell lipoma Slowly growing subcutaneous tumor; Mature adipocytes and uniform spindle particularly common on the shoulder cells within a mucinous matrix; girdle, nape, and upper back; more scattered mast cells common in men Leiomyoma/leiomyosarcoma Often painful; most common on the Eosinophilic cytoplasm with blunt-ended shoulder or upper arm cigar-shaped nuclei; long rather than short fascicles Malignant peripheral nerve Association with neurofibromatosis Wavy or buckled nuclei; perivascular sheath tumor condensation
CD34 (+), CD99 (+), factor XIIIa (6), SMA (2), S-100 (2), EMA (6), desmin (2), bcl-2 (+) CD34 (6), factor XIIIa (+), SMA (6), S-100 (2), EMA (2), desmin (2), bcl-2 (2) CD34 (+), factor XIIIa (6), vimentin (+), SMA (6), S-100 (2), EMA (2), desmin (2), bcl-2 (6) Vimentin (+), CD34 (6), EMA (6), desmin (2)
Vimentin (+), CD 68 (+), CD34 (2), S-100 (2) CD34 (+), CD99 (+), vimentin (+), S-100 (2), SMA (2)
SMA (+), desmin (+), CD34 (2), bcl-2 (2), MT (+) S-100 (+), bcl-2 (6), SMA (6)
SMA, smooth muscle actin; EMA, epithelial membrane antigen; MT, Masson’s trichrome.
The biological behavior of myxoid SFTs has not been described in detail and is still being investigated because of the tumors’ rare incidence. Lau et al14 reported that myxoid SFTs are associated with an indolent clinical course and low potential for recurrence and metastasis, on the basis of their experience with 3 cases. The 3 new cases described by Dantey and Cooper10 also demonstrated a favorable prognosis. None of these cases showed pathologic atypia, recurrence, or metastasis during a follow-up period of 3–87 months. According to the literature review conducted by Lau et al,14 8 studies with a total of 14 cases of myxoid SFT have been reported worldwide. Taken together with the previously mentioned cases, our case provides additional support for the tendency of myxoid SFTs to have a benign or favorable course. Focal myxoid stromal change is a well-recognized feature of SFTs. However, predominant or extensive myxoid appearances have rarely been reported in the recent dermatologic literature. To our knowledge, this is the first reported case of presentation on the palm. Recognition of this uncommon morphologic subset of SFT is important because of possible confusion, particularly in cases of small biopsy specimens, with a variety of myxoid spindle cell tumors with varying biologic potential. Thus, we report this case of a rare occurrence of SFT with myxoid stromal change in the skin, which initially suggested the diagnosis of verruca, and highlight the fact that SFT should be considered in the differential diagnosis of various superficial spindle cell tumors accompanied by myxoid change. Copyright 2014 Wolters Kluwer Health, Inc. All rights reserved.
REFERENCES
1. Hardisson D, Cuevas-Santos J, Contreras F. Solitary fibrous tumor of the skin. J Am Acad Dermatol. 2002;46:S37–S40. 2. Chan JK. Solitary fibrous tumour—everywhere, and a diagnosis in vogue. Histopathology. 1997;31:568–576. 3. Gold JS, Antonescu CR, Hajdu C, et al. Clinicopathologic correlates of solitary fibrous tumors. Cancer. 2002;94:1057–1068. 4. Erdag G, Qureshi HS, Patterson JW, et al. Solitary fibrous tumors of the skin: a clinicopathologic study of 10 cases and review of the literature. J Cutan Pathol. 2007;34:844–850. 5. Morimitsu Y, Nakajima M, Hisaoka M, et al. Extrapleural solitary fibrous tumor: clinicopathologic study of 17 cases and molecular analysis of the p53 pathway. APMIS. 2000;108:617–625. 6. Soldano AC, Meehan SA. Cutaneous solitary fibrous tumor: a report of 2 cases and review of the literature. Am J Dermatopathol. 2008;30:54–58. 7. Musyoki FN, Nahal A, Powell TI. Solitary fibrous tumor: an update on the spectrum of extrapleural manifestations. Skeletal Radiol. 2012;41:5–13. 8. de Saint Aubain Somerhausen N, Rubin BP, Fletcher CD. Myxoid solitary fibrous tumor: a study of seven cases with emphasis on differential diagnosis. Mod Pathol. 1999;12:463–471. 9. Morgan MB, Smoller BR. Solitary fibrous tumors are immunophenotypically distinct from mesothelioma(s). J Cutan Pathol. 2000;27:451–454. 10. Dantey K, Cooper K. Myxoid solitary fibrous tumor: a study of three cases. Int J Surg Pathol. 2013;21:358–362. 11. Yap T, Hamzah L, Oshowo A, et al. Myxoid solitary fibrous tumour of the ischiorectal fossa. Eur J Surg Oncol. 2003;29:98–100. 12. Yilmaz C, Kabatas S, Ozen OI, et al. Solitary fibrous tumor. J Clin Neurosci. 2009;16:1578–1581. 13. Wood L, Fountaine TJ, Rosamilia L, et al. Cutaneous CD34+ spindle cell neoplasms: histopathologic features distinguish spindle cell lipoma, solitary fibrous tumor, and dermatofibrosarcoma protuberans. Am J Dermatopathol. 2010;32:764–768. 14. Lau SK, Weiss LM, Chu PG. Myxoid solitary fibrous tumor: a clinicopathologic study of three cases. Virchows Arch. 2009;454:189–194.
www.amjdermatopathology.com |
573
