|LETTER TO EDITOR
|Year : 2011 | Volume
| Issue : 1 | Page : 42-43
Atypical presentation of Becker's melanosis
Jayasree Manoj1, Feroze Kaliyadan1, KR Hiran2
1 Department of Dermatology, Amrita Institute of Medical Sciences and Research Centre, Elamakkara PO, Kochi-26, Kerala, India
2 Department of Pathology, Amrita Institute of Medical Sciences and Research Centre, Elamakkara PO, Kochi-26, Kerala, India
|Date of Web Publication||21-Apr-2011|
Department of Dermatology, Amrita Institute of Medical Sciences and Research Centre, Elamakkara PO, Kochi-26, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Manoj J, Kaliyadan F, Hiran K R. Atypical presentation of Becker's melanosis. Indian Dermatol Online J 2011;2:42-3
|How to cite this URL:|
Manoj J, Kaliyadan F, Hiran K R. Atypical presentation of Becker's melanosis. Indian Dermatol Online J [serial online] 2011 [cited 2020 Feb 23];2:42-3. Available from: http://www.idoj.in/text.asp?2011/2/1/42/79856
Becker's melanosis typically presents as a single, asymptomatic, irregular, tan-to-brown patch, most commonly located over the shoulder, upper chest, or back.  We present an atypical case of Becker's melanosis presenting as a single lesion on the knee.
A 28-year-old male presented to our out-patient department with a history of an asymptomatic hyperpigmented patch on the left knee which appeared at around 14 years of age, and was gradually increasing in size for about 7 years. Cutaneous examination revealed a solitary hyperpigmented macule with irregular margins of size approximately 10×10 cm over the left knee [Figure 1]. There appeared to be minimally excessive coarse hair over the lesion, compared to the normal surrounding skin.
There was no history of other systemic illnesses or any other musculo-skeletal deformities. Histopathological examination of skin lesion demonstrated features of Becker's melanosis---the epidermis showing mild acanthosis and hyperkeratosis, with regular elongation of rete-ridges and the basal layer showing prominent hyperpigmentation [Figure 2].
|Figure 2: Histopathology showing mild acanthosis and prominent basal pigmentation (H and E, ×20)|
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Classically, Becker's nevus often appears as a single, sharply demarcated, unilateral, hyperpigmented, tan-colored macule over the shoulder or pectoral area in a teenage male.  Various associated abnormalities have been described along with Becker's nevus, including unilateral hypoplasia of the breast, aplasia of the ipsilateral pectoralis major muscle, ipsilateral limb shortening, localized lipoatrophy, spina bifida, scoliosis, pectus carinatum, congenital adrenal hyperplasia, and an accessory scrotum. Multiple Becker's nevi can occur rarely. , There are very few reports of Becker's nevi occurring in atypical sites like the legs.  Bilateral involvement is very rare. , An interesting study by AlGhamdi et al. attempted a clinic-pathological correlation for atypical cases of Becker's melanosis. Of the 11 cases included, 10 had a atypical sites of involvement and 2 cases (including 1 with atypical site) had bilateral involvement. Other atypical features included the absence of hypertrichosis and unusual age of onset. Histologically, all their cases demonstrated acanthosis and increased basal melanocyte numbers. Ten patients manifested elongation of the rete-ridges and basal pigmentation, while seven had melanophages. Two patients also showed sebaceous gland hyperplasia. Only one patient exhibited smooth muscle hyperplasia.  Another case series by Alfadley et al. also reported 12 cases. Atypical features reported were similar ---atypical site, late age of onset, and absence of hypertrichosis.  Hsu et al. have reported a case similar to ours, with Becker's melanosis occurring over the leg without associated hypertrichosis. 
The exact pathogenesis of Becker's nevus---typical or atypical, still remains unknown. It is assumed that androgens may play a role in Becker melanosis as evidenced by its peripubertal development, male preponderance, hypertrichosis, occasional development of acneiform lesions within the patch, and rare association with accessory scrotum in the genital region. In addition, a significant increase in the number of androgen receptors in Becker melanosis lesional skin has been reported. 
Our case is presented to highlight the fact that Becker's melanosis must be considered as a diagnostic possibility even in atypical sites even without hypertrichosis, if the history and clinical features are suggestive.
| References|| |
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[Figure 1], [Figure 2]