Desmoplastic leiomyosarcoma of the skin.

This report focuses on two unusual cases of cutaneous leiomyosarcoma composed of sparse numbers of neoplastic cells embedded in abundant sclerotic stroma throughout the entire neoplasm. To the best of our knowledge, only one example of this rare lesion has been described previously as "sclerotic primary cutaneous leiomyosarcoma." However, the resemblance of this tumor to other desmoplastic tumors of the skin is striking and, therefore, we propose the term desmoplastic leiomyosarcoma of the skin for this neoplasm. Because of the sparse cellularity and the abundant stroma, desmoplastic leiomyosarcoma of the skin can be easily misinterpreted, especially in small biopsies. It should be included in the differential diagnosis of inflammatory skin diseases associated with sclerosis, such as radiation dermatitis, and of desmoplastic tumors of the skin, including desmoplastic melanocytic nevus, desmoplastic melanoma, and desmoplastic squamous cell carcinoma.