Intradermal proliferative fasciitis in childhood: a potential diagnostic pitfall

Proliferative fasciitis (PF) is a pseudosarcomatous proliferation which typically occurs in the subcutaneous tissue and fascia. Although patients are characteristically middle-aged people, occasionally PF can arise in children. Histologically, PF is characterized by a proliferation of large ganglion-like and spindle-shaped cells which, especially in childhood, may exhibit high mitotic activity, but no atypical mitoses. We report a case of PF in the dermis of a 13-year-old boy. This is the first case of PF primarily arising in the dermis. Apart from the unusual site, another intriguing finding was the presence of rare atypical mitoses, a feature which has not been previously emphasized in PF. Awareness that PF may occur in the dermis, exhibiting occasional atypical mitoses, is crucial to avoid a misdiagnosis of malignancy.