Hypocellular medallion-like dermal dendrocyte hamartoma (plaque-like CD34-positive dermal fibroma).

Medallion-like dermal dendrocyte hamartoma (MLDDH) is a recently described congenital dermal neoplasm. Only 11 cases have been reported in the English literature and therefore its clinical and pathological manifestations are not completely defined. We report the case of a 20-year-old male presenting with a round, erythematous, atrophic plaque on the midline of the anterior aspect of the neck. The lesion was asymptomatic and was stable since birth. A skin biopsy was performed. Histological examination showed a band like hypocellular fibrotic area in the superficial reticular dermis, which did not spread to subcutaneous tissue. The cells were CD34-positive and S100 and CD56-negative. Elastic fibers were present. Altogether the morphological and immunostaining features were neither suggestive of dermatofibrosarcoma protuberans nor neurofibroma. Thus, the pathological findings were consistent with MLDDH. Clinical differential diagnosis includes anetoderma, aplasia cutis, or atrophic DFSP. Histological differential was made with atrophic scar and striae distensae. Although the histological findings were not identical to those described recently as characteristic, the clinical features were suggestive enough to make the diagnosis of MLDDH. Therefore in our experience, the MLDDH spectrum might include lesions with variable cellular density, which can show similar clinical manifestations.