Unusual Congenital Multiple Clustered Dermatofibroma: First Reported Case on the Face.

A 13-month-old boy was referred to us for examination of multiple nodules on his right forehead. The lesions were first noticed at birth and had increased during the past several months. On physical examination, firm, pink-tan nodules, ranging in size from 2 to 10 mm were clustered in a linear arrangement (Fig. 1a). Dermoscopy showed a homogenous pigment network (not shown). A biopsy specimen showed a nodular lesion in the reticular dermis and superficial subcutis (Fig. 1b). The tumour consisted of short fascicles of lightly eosinophilic spindle cells intermingled with collagen bundles (Fig. 1c). There was no significant atypia or pleomorphism in the tumour cells. The overlying epidermis showed slight acanthosis with basal hyperpigmentation. Immunohistochemistry studies showed strong positivity for alpha-smooth muscle actin (α-SMA) (Fig. 1d) and moderate positivity for factor XIIIa (Fig. 1e) and D2-40. The tumour cells were negative for CD34 (Fig. 1f), S-100 protein, SOX10, pancytokeratin (AE1/3), ERG, epithelial membrane antigen and factor VIII. Expression of trimethylation of histone H3 lysine 27 was intact. Thus, this case was diagnosed as MCD.