Aims: Cutaneous leiomyosarcomas (LMS) are rare in comparison with their deep-seated soft tissue and uterine counterparts, and have been poorly characterized. The aim was to verify whether the clinical behaviour of purely dermal LMS is different from that of LMS with minimal subcutis invasion.
Methods and results: Twenty-one purely dermal LMS and 15 dermal LMS with minimal subcutis extension were analysed. Tumours developed in 27 men and nine women (age range 29-91 years); most tumours showed a fasciculated (n = 23), pilar-type (n = 12) and pleomorphic (n = 1) pattern. During the follow-up period (range 2-192, mean 41 months) recurrences occurred in 1/16 (6.2%) of tumours confined to the dermis and in 2/11 (18.1%) tumours with minimal subcutis extension. The three recurrent tumours were high-grade LMS, two of which exhibited myxoid areas. One patient with a pleomorphic dermal LMS with minimal extension into fat developed distant metastases 15 years after diagnosis.
Conclusions: For LMS involving the skin, it is advisable to recognize and indicate in the histopathology report the depth of dermal and/or subcutaneous extension, since even minimal subcutaneous involvement may be associated with late local recurrences and/or distant metastases, and therefore appropriate and long-term follow-up is needed.