Neural variant of fetal rhabdomyoma and naevoid basal cell carcinoma syndrome.

A 15-year-old boy with the characteristic features of the naevoid basal cell carcinoma syndrome presented with a retroperitoneal mass. The tumour showed morphological features of a still ill-defined variant of fetal rhabdomyoma, characterized by well-differentiated nerve fibres admixed with immature striated muscle cells, similar to neuromuscular choristoma. Four cases of fetal rhabdomyoma and naevoid basal cell carcinoma syndrome have been previously reported. The behaviour of this tumour has been benign, although a complete excision was impossible due to its close relation with abdominal vascular trunks.