[Acquired benign myofibroma of the skin (adult myofibroma)].

Adult myofibroma is an acquired skin tumour that is histologically identical to infantile myofibroma. Histologically, four tumour variants can be distinguished: leiomyoma type, cellular spindle cell type, haemangiopericytoma or glomus type, and biphasic type. Practical help in diagnosis is supplied by the hamartomatous composition of the leiomyoma-type, hyalinized spindle cell whorls, endothelium-lined haemangiopericytoma-like vascular channels, and desmin-negative, muscle-actin-positive myofibroblasts, which may show spindle cell or undifferentiated mesenchymal cell differentiation. The tumours clinically present as firm, occasionally bluish cutaneous or subcutaneous nodules. Adult myofibroma should be recognized as a distinct benign neoplasm, most probably of vascular origin. Clinicians and dermatopathologists must be aware that lesions identical to those of infantile myofibroma can occur in adults.