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Unknown: Papules on the knees

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Unknown: Papules on the knees
Valeria P Boccaletti MD1, Roberto Ricci MD2, Giuseppe De Panfilis MD1
Dermatology Online Journal 17 (5): 12

1. Unit of Dermatology, Dept. of Surgical Sciences
2. Dept of Pathology
Parma University Hospital, Parma, Italy.,

Case synopsis

Figure 1 Figure 2

A 12-year-old girl affected with Down syndrome presented with a two year history of several mildly pruritic, enlarging hyperkeratotic papules distributed symmetrically over the knees (Figure 1) and the elbows. Her family history was negative for any cutaneous or systemic disorder. She was also affected by primary hypothyroidism controlled by levothyroxin (37.5 μg/day) and growth hormone deficiency treated with growth hormone.

Figure 3 Figure 4

Physical examination revealed multiple reddish papules, most of which were umbilicated with a central keratotic plug. The papules and plaques were disposed in several serpiginous lines, some within hyperpigmented macules (Figure 2). A biopsy specimen from the knee was submitted for histopathologic evaluation (Figure 3 and Figure 4).

What is the diagnosis?


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