British Journal of Dermatology (1977) 96, 287.
An acne-free naevus W.J.CUNLIFFE, R.D.EAD, W.H.D.PERERA AND M.B.HODGINS* Department of Dermatology, The General Infirmary, Leeds, and * Department of Dermatology & Biochemistry, University of Glasgow Accepted for publication 16 August 1976
SUMMARY
Investigation of rare disorders may sometimes help in the understanding of common problems. We describe a patient with an unusual and previously unreported acnc-frce naevus occurring in an area severely affected by acne. Investigation revealed smaller sebaceous glands, a reduced sebum excretion rate, decreased number oiCorynebacterium acnes in the pilosebaccous ducts and a reduced conversion of testosterone to 5 oidihydrotestosterone in the areas which were free of acne compared with acnebearing skin. The results of these investigations support some of the suggested mechanisms responsible for the development of acne. CASE REPORT
The patient was a 17-year-old male who had a 3-year history of acne. Examination revealed severe papulo-pustular acne on his back and chest but only mild facial acne. On his back there were four well defined symmetrical areas that were completely free of acne. They were situated in the region of the angles of both scapulae (Fig. i) and on the lateral aspects of both shoulders. Apart from the lack of acne, the skin in these areas appeared completely normal to the naked eye. The rest of his back was covered with severe acne which extended down to his waist. No other abnormality was detected on general examination. INVESTIGATIONS
The following investigations were performed on the acne-free and the acne-bearing skin of the back: (i) Surface microscopy to estimate the number and size of the pilosebaceous ducts by the method of Cunliffe, Forster & Williams (1974). (2) Skin surface biopsy by the method of Marks & Dawber (1971). (3) Histological examination of biopsy specimens. (4) The sebum excretion rate was measured by the method of Strauss & Pochi (1961), as modified by Cunliffe & Shuster (1969), on three separate occasions. (5) Surface lipid analysis. Surface lipid was collected using an ether soaked sponge after preparation of the skin with absorbent papers. Thin layer chromatography was performed by the method of Cotterill et al. (1971). (6) Surface bacteriological samples were taken with a swab and pilosebaceous duct samples were obtained by the method of Holland et al. (1974). (7) Biopsies were taken for studies of steroid metabolism. The tissue was incubated with 1,2-^H testosterone (30 lunol/l) dissolved in 2 0 ml Eagle's medium for 2 h at 37 C under 95% 02 + 5% CO,. After incubation the medium was removed and the tissue washed twice with 4 0 ml ice cold Eagle's medium. The washings were combined with the incubation medium. The tissue was washed twice more with 4 0 ml ice cold Tris-sucrose. The washed tissue was suspended in 2-0 ml Tris-KCl-EDTA, frozen and homogenized in a French pressure cell. The steroids were then extracted from the homogenate with chloroform/methanol. Steroids in medium and tissue were isolated and determined by a standard method. 287
288
W.J.Cunliffe et al.
FIGURE I. Shows symmetrical, well defined areas of acne-free skin on the back.
We would like to have carried out further investigations such as, for example, whether the acne-free skin reacted in the same way as the acne-bearing skin to mediators of inflammation. Measurement of sweat production in both areas could have been interesting. We felt, however, that we were not justified in carrying out any further investigations in this patient as we were not able to improve his acne by treatment and any biopsy taken from either area resulted in rapid keloid formation. RESULTS
Surface microscopy revealed no difference in the number of pilosebaceous units between the acne-free and the acne-bearing skin (Table i). The ducts in the acne areas were, however, larger than those in the acne-free skin (Table i). Histological examination of the biopsy specimens showed that the sebaceous glands in the acne-free areas were smaller than in the acne-bearing skin but planimetry was not performed. Microscopic examination of the skin surface biopsy showed that the pilosebaceous units from the acne-bearing skin contained more keratin than those of the acne-free area (Table i). The sebum excretion rate in the acne-bearing skin was approximately 30",, greater than in the acnefree skin (Table i) and there was an increase in the percentage of squalene and wax esters with a decrease in triglycerides in the acne-bearing skin on surface lipid analysis (Table i). Surface bacteriology revealed no difference between the acne-free and the acne-bearing skin but pilosebaceous duct samples from the acne-free area contained smaller numbers of Corynebacterium acnes than in the acne-bearing skin. The numbers of Staphylococcus epidermidis were about the same from both areas (Table 2).
An acne-free naevus
289
TABLE I. Comparison of findings in the acne-free and acne-bearing skin
No. of pilosebaceous ducts/cm ^ Surface area of pilosebaceous ducts (mm^) y^ of hairs coated with keratin Degree of keratin coating (on a 1-4 scale) Sebum excretion rate (//g/cm ^/min.) Thin layer chromatography Squalene Wax ester Triglycerides Free fatty acids
Acne-free skin
Acne-bearing skin
79
74
O'OO35
0008
587c
71%
2
2-3
0-17
0-30
36% 32%
ro",,
26X 42% 22%
IO"-;;
The studies of steroid metabolism demonstrated an increased uptake of labelled testosterone in the acne-bearing skin compared to the acne-free skin and also an increased conversion to 5a dihydrotestosterone in these areas (Table 3). We realize that the steroid assay was related to the weight of the biopsy and not to the size of the sebaceous glands. The objection here is that the increased uptake and conversion of labelled testosterone may just be due to the presence of larger glands in the acne-bearing skin. In other words the increased uptake is a result rather than a cause of larger glands. At present there is no easy solution to this problem. TABLE 2. Comparison of number of bacteria from surface and pilosebaceous duct samples from the acnc-free and acne-bearing skin Acne-frec skin
Acne-bearing skin
2 0 X 10^ 5 2 X 10''
2-4 X 10^ 4 8 X 10*
7-0 X 10^ 2-OX I0-'
85x10'
Surface samples Staph. epidermidis Corynebacterium acnes
Pilosebaceous duct samples Staph. epidermidis Corynebacterium acnes
5 1 X 10^
DISCUSSION
It is difficult to draw any firm conclusions from a report of only one case; however, several findings suggest that some of the present theories concerning the pathogenesis of acne may be correct and others incorrect. The lack of acne in the acne free areas was certainly not due to fewer sebaceous glands but the glands in these areas were smaller and not unexpectedly produced less sebum. This would seem to add further support to the well established fact that acne and seborrhoea are closely linked. There is evidence from Kligman, Wheatley & Mills (1970) that squalene is almost as potent as free fatty acids in terms of comedogenecity. The fact that percentages of free fatty acids were the same from both types of skin but the percentage of squalene was elevated in acne-bearing skin may
290
WJ.Ctmlijfe et al. TABLE 3. Results of radio-labelled testosterone studies % Total c.p.m. retained in skin
Acne-free skin Acne-bearing skin Acne-bearing skin
458 7-27 7'10
% Total c.p.ni. as ^H 5 v D H T Skin
Medium
O'Bo
0-58 0 81 095
i'35 I'66
support the suggestion that squalene is perhaps more important in the development of obstructed lesions than fatty acids. Caution is needed in interpreting the bacteriological data as it is known that numbers of bacteria vary considerably in adjacent areas of the skin. The finding of more Corynebacterium acnes in the ducts from the acne sites could support the possible important role oi Corynebacterium acnes in the aetiology of acne (Leyden et al., 1975); alternatively, it could simply be related to the increased size and amounts ofkeratin in these ducts. Surprisingly, if this is true, there was no increase in the numhti oi Staphylococcus epidermidis found in the ducts in the acne areas. Cooper et al. (1976) have recently described a patient who is almost the reverse of our case. Their patient had severe acne on one side of the body and less severe acne on the other. The side with severe acne showed increased seborrhoea, increased muscle bulk and increased sweating. Radio-labelled studies showed an increased conversion of dehydroepiandrosterone to androstenedione. There was no increased conversion of testosterone to 5a dihydrotestosterone, in contrast to our patient. They suggested that the reasons for the unilateral severity of the acne was due to an abnormality of handling of adrenal androgen. In our case there was a complete failure of acne to develop in the naevus areas rather than severe acne on one side and mild acne on the other. All the findings in our case could be explained by a decreased rate of conversion of testosterone to 53 dihydrotestosterone resulting in a smaller sebaceous gland, reduced sebum excretion rate, less keratin in the ducts, possibly an altered lipid composition and reduced C acnes numbers in the duct. The occurrence of this 'non-acne naevus' is presumably due to an abnormal end-organ response to circulating androgen. Unfortunately, for us, we have not been able to find any further cases, as investigation of this type of lesion may well prove to be very rewarding in the understanding of acne. REFERENCES COOPER, M.F., HAY, J.B., MCGIBBON, D . & SHUSTER, S. (1976) Androgen metabolism and sebaceous activity in clonal acne. Journal of Investigative Dermatology, 66, 261. COTTERILL, J.A., CUNLIFFE, W.J., WILLIAMSON, B . & FDRSTER, R.A. (1971) A semi-quantitative method for the
biochemical analysis of sebum. British Journal of Dermatology, 85, 35. CUNLIFFE, W.J., FORSTER, R.A. & WILLIAMS, M . (1974) A surface microscope for clinical and laboratory use.
British Journal of Dermatology, 90, 619. CUNLIFFE, W.J. & SHUSTER, S. C1969) The rate of sebum excretion in man. British Journal of Dermatology, 81, 697. HOLLAND, K.T., ROBERTS, C D . , CUNLIFFE, W.J. & WILLIAMS, M . (1974) A technique for sampling microorganisms
from the pilosebaceous ducts. Journal of Applied Bacteriology, 37, 289. KLIGMAN, A.M., WHEATLEY, U . R . & MILLS, O . H . (1970) Comedogenicity of human sebum. Archives of Derma-
tology, 102, 267. LEYDEN, J.J., MCGINLEY, K.J., MILLS, O.H. & KLIGMAN, A.M. (1975) Age related changes in the resident flora
of the human face. Journal of Investigative Dermatotogy, 65, 379. MARKS, R. & DAWBER, R.P.R. (1971) Skin surface biopsy, an improved technique for examination of the horny layer. British Journal of Dermatology, 84, 117.
STRAUSS, J.S. & POCHI, P.E. (1961) The quantitative gravimetric determination of sebum production. Journal of Investigative Dermatology, 36, 293.
An acne-free naevus W.J.CUNLIFFE, R.D.EAD, W.H.D.PERERA AND M.B.HODGINS* Department of Dermatology, The General Infirmary, Leeds, and * Department of Dermatology & Biochemistry, University of Glasgow Accepted for publication 16 August 1976
SUMMARY
Investigation of rare disorders may sometimes help in the understanding of common problems. We describe a patient with an unusual and previously unreported acnc-frce naevus occurring in an area severely affected by acne. Investigation revealed smaller sebaceous glands, a reduced sebum excretion rate, decreased number oiCorynebacterium acnes in the pilosebaccous ducts and a reduced conversion of testosterone to 5 oidihydrotestosterone in the areas which were free of acne compared with acnebearing skin. The results of these investigations support some of the suggested mechanisms responsible for the development of acne. CASE REPORT
The patient was a 17-year-old male who had a 3-year history of acne. Examination revealed severe papulo-pustular acne on his back and chest but only mild facial acne. On his back there were four well defined symmetrical areas that were completely free of acne. They were situated in the region of the angles of both scapulae (Fig. i) and on the lateral aspects of both shoulders. Apart from the lack of acne, the skin in these areas appeared completely normal to the naked eye. The rest of his back was covered with severe acne which extended down to his waist. No other abnormality was detected on general examination. INVESTIGATIONS
The following investigations were performed on the acne-free and the acne-bearing skin of the back: (i) Surface microscopy to estimate the number and size of the pilosebaceous ducts by the method of Cunliffe, Forster & Williams (1974). (2) Skin surface biopsy by the method of Marks & Dawber (1971). (3) Histological examination of biopsy specimens. (4) The sebum excretion rate was measured by the method of Strauss & Pochi (1961), as modified by Cunliffe & Shuster (1969), on three separate occasions. (5) Surface lipid analysis. Surface lipid was collected using an ether soaked sponge after preparation of the skin with absorbent papers. Thin layer chromatography was performed by the method of Cotterill et al. (1971). (6) Surface bacteriological samples were taken with a swab and pilosebaceous duct samples were obtained by the method of Holland et al. (1974). (7) Biopsies were taken for studies of steroid metabolism. The tissue was incubated with 1,2-^H testosterone (30 lunol/l) dissolved in 2 0 ml Eagle's medium for 2 h at 37 C under 95% 02 + 5% CO,. After incubation the medium was removed and the tissue washed twice with 4 0 ml ice cold Eagle's medium. The washings were combined with the incubation medium. The tissue was washed twice more with 4 0 ml ice cold Tris-sucrose. The washed tissue was suspended in 2-0 ml Tris-KCl-EDTA, frozen and homogenized in a French pressure cell. The steroids were then extracted from the homogenate with chloroform/methanol. Steroids in medium and tissue were isolated and determined by a standard method. 287
288
W.J.Cunliffe et al.
FIGURE I. Shows symmetrical, well defined areas of acne-free skin on the back.
We would like to have carried out further investigations such as, for example, whether the acne-free skin reacted in the same way as the acne-bearing skin to mediators of inflammation. Measurement of sweat production in both areas could have been interesting. We felt, however, that we were not justified in carrying out any further investigations in this patient as we were not able to improve his acne by treatment and any biopsy taken from either area resulted in rapid keloid formation. RESULTS
Surface microscopy revealed no difference in the number of pilosebaceous units between the acne-free and the acne-bearing skin (Table i). The ducts in the acne areas were, however, larger than those in the acne-free skin (Table i). Histological examination of the biopsy specimens showed that the sebaceous glands in the acne-free areas were smaller than in the acne-bearing skin but planimetry was not performed. Microscopic examination of the skin surface biopsy showed that the pilosebaceous units from the acne-bearing skin contained more keratin than those of the acne-free area (Table i). The sebum excretion rate in the acne-bearing skin was approximately 30",, greater than in the acnefree skin (Table i) and there was an increase in the percentage of squalene and wax esters with a decrease in triglycerides in the acne-bearing skin on surface lipid analysis (Table i). Surface bacteriology revealed no difference between the acne-free and the acne-bearing skin but pilosebaceous duct samples from the acne-free area contained smaller numbers of Corynebacterium acnes than in the acne-bearing skin. The numbers of Staphylococcus epidermidis were about the same from both areas (Table 2).
An acne-free naevus
289
TABLE I. Comparison of findings in the acne-free and acne-bearing skin
No. of pilosebaceous ducts/cm ^ Surface area of pilosebaceous ducts (mm^) y^ of hairs coated with keratin Degree of keratin coating (on a 1-4 scale) Sebum excretion rate (//g/cm ^/min.) Thin layer chromatography Squalene Wax ester Triglycerides Free fatty acids
Acne-free skin
Acne-bearing skin
79
74
O'OO35
0008
587c
71%
2
2-3
0-17
0-30
36% 32%
ro",,
26X 42% 22%
IO"-;;
The studies of steroid metabolism demonstrated an increased uptake of labelled testosterone in the acne-bearing skin compared to the acne-free skin and also an increased conversion to 5a dihydrotestosterone in these areas (Table 3). We realize that the steroid assay was related to the weight of the biopsy and not to the size of the sebaceous glands. The objection here is that the increased uptake and conversion of labelled testosterone may just be due to the presence of larger glands in the acne-bearing skin. In other words the increased uptake is a result rather than a cause of larger glands. At present there is no easy solution to this problem. TABLE 2. Comparison of number of bacteria from surface and pilosebaceous duct samples from the acnc-free and acne-bearing skin Acne-frec skin
Acne-bearing skin
2 0 X 10^ 5 2 X 10''
2-4 X 10^ 4 8 X 10*
7-0 X 10^ 2-OX I0-'
85x10'
Surface samples Staph. epidermidis Corynebacterium acnes
Pilosebaceous duct samples Staph. epidermidis Corynebacterium acnes
5 1 X 10^
DISCUSSION
It is difficult to draw any firm conclusions from a report of only one case; however, several findings suggest that some of the present theories concerning the pathogenesis of acne may be correct and others incorrect. The lack of acne in the acne free areas was certainly not due to fewer sebaceous glands but the glands in these areas were smaller and not unexpectedly produced less sebum. This would seem to add further support to the well established fact that acne and seborrhoea are closely linked. There is evidence from Kligman, Wheatley & Mills (1970) that squalene is almost as potent as free fatty acids in terms of comedogenecity. The fact that percentages of free fatty acids were the same from both types of skin but the percentage of squalene was elevated in acne-bearing skin may
290
WJ.Ctmlijfe et al. TABLE 3. Results of radio-labelled testosterone studies % Total c.p.m. retained in skin
Acne-free skin Acne-bearing skin Acne-bearing skin
458 7-27 7'10
% Total c.p.ni. as ^H 5 v D H T Skin
Medium
O'Bo
0-58 0 81 095
i'35 I'66
support the suggestion that squalene is perhaps more important in the development of obstructed lesions than fatty acids. Caution is needed in interpreting the bacteriological data as it is known that numbers of bacteria vary considerably in adjacent areas of the skin. The finding of more Corynebacterium acnes in the ducts from the acne sites could support the possible important role oi Corynebacterium acnes in the aetiology of acne (Leyden et al., 1975); alternatively, it could simply be related to the increased size and amounts ofkeratin in these ducts. Surprisingly, if this is true, there was no increase in the numhti oi Staphylococcus epidermidis found in the ducts in the acne areas. Cooper et al. (1976) have recently described a patient who is almost the reverse of our case. Their patient had severe acne on one side of the body and less severe acne on the other. The side with severe acne showed increased seborrhoea, increased muscle bulk and increased sweating. Radio-labelled studies showed an increased conversion of dehydroepiandrosterone to androstenedione. There was no increased conversion of testosterone to 5a dihydrotestosterone, in contrast to our patient. They suggested that the reasons for the unilateral severity of the acne was due to an abnormality of handling of adrenal androgen. In our case there was a complete failure of acne to develop in the naevus areas rather than severe acne on one side and mild acne on the other. All the findings in our case could be explained by a decreased rate of conversion of testosterone to 53 dihydrotestosterone resulting in a smaller sebaceous gland, reduced sebum excretion rate, less keratin in the ducts, possibly an altered lipid composition and reduced C acnes numbers in the duct. The occurrence of this 'non-acne naevus' is presumably due to an abnormal end-organ response to circulating androgen. Unfortunately, for us, we have not been able to find any further cases, as investigation of this type of lesion may well prove to be very rewarding in the understanding of acne. REFERENCES COOPER, M.F., HAY, J.B., MCGIBBON, D . & SHUSTER, S. (1976) Androgen metabolism and sebaceous activity in clonal acne. Journal of Investigative Dermatology, 66, 261. COTTERILL, J.A., CUNLIFFE, W.J., WILLIAMSON, B . & FDRSTER, R.A. (1971) A semi-quantitative method for the
biochemical analysis of sebum. British Journal of Dermatology, 85, 35. CUNLIFFE, W.J., FORSTER, R.A. & WILLIAMS, M . (1974) A surface microscope for clinical and laboratory use.
British Journal of Dermatology, 90, 619. CUNLIFFE, W.J. & SHUSTER, S. C1969) The rate of sebum excretion in man. British Journal of Dermatology, 81, 697. HOLLAND, K.T., ROBERTS, C D . , CUNLIFFE, W.J. & WILLIAMS, M . (1974) A technique for sampling microorganisms
from the pilosebaceous ducts. Journal of Applied Bacteriology, 37, 289. KLIGMAN, A.M., WHEATLEY, U . R . & MILLS, O . H . (1970) Comedogenicity of human sebum. Archives of Derma-
tology, 102, 267. LEYDEN, J.J., MCGINLEY, K.J., MILLS, O.H. & KLIGMAN, A.M. (1975) Age related changes in the resident flora
of the human face. Journal of Investigative Dermatotogy, 65, 379. MARKS, R. & DAWBER, R.P.R. (1971) Skin surface biopsy, an improved technique for examination of the horny layer. British Journal of Dermatology, 84, 117.
STRAUSS, J.S. & POCHI, P.E. (1961) The quantitative gravimetric determination of sebum production. Journal of Investigative Dermatology, 36, 293.
