Multiple firm, reddish-brown papules and nodules on shoulder and arm

The reported case is a 39-year old man who was referred to dermatology clinic with a 10 years history of multiple papules and nodules on his lateral aspect of upper shoulder and the wholeright arm (figure 1). the lesions became larger and increased in number during this period. they got painful especially on exposure to cold. he was otherwise healthy. he had no family history of any significant disease. in dermatologic physical examination, there were grouped, segmental, firm, reddish-brown papules and nodules on the lateral aspect of shoulder and the whole arm. lesions were painful especially with deep palpation and pseudo darier sign was positive. general physical examination was normal. an excisional biopsy was done fromone of the lesions.