Clinical Variables Influencing Outcomes in Patients with Atypical Intradermal Smooth Muscle Neoplasms (Formerly Cutaneous Leiomyosarcomas): Single-Institution Study of 95 Surgical Patients.

BACKGROUND

Atypical intradermal smooth muscle neoplasm, also commonly termed cutaneous leiomyosarcoma, is a soft tissue tumor with a low risk of aggressive behavior. These lesions arise in the dermis with possible superficial subcutaneous extension, demonstrate cytologic atypia, and often show mitotic activity.

METHODS

A retrospective review of patient demographics, tumor characteristics, and treatment methods was conducted in a consecutive series of patients presenting to MD Anderson Cancer Center (MDACC) from 2002 to 2021 (n = 95). All pathology was reviewed by MDACC pathologists and determined to be atypical intradermal smooth muscle neoplasm.

RESULTS

Median age at diagnosis was 58 years (range 22-86), and 74% were male. Ninety-five percent (n = 90) of patients identified as White, non-Hispanic. Most tumors were slow-growing, solitary, and painless nodules. Tumors were in the lower extremities (44.2%), followed by the upper extremity (28.4%), trunk (22.1%), and head and neck (5.2%). All patients (n = 44, 46.3%) who had a punch/incisional biopsy for diagnostic purposes had a subsequent tumor excision. Unplanned excision or excisional biopsy was performed on the remaining 46 (48%) patients. Of this subset, 41 of the 46 aforementioned patients (89%) had positive margins and underwent re-excision. Final pathology in 25/38 (66%) re-excision specimens was negative for residual tumor despite an initial positive margin. Two patients in the cohort had local recurrence 2 and 3 years after initial surgery. Both patients had positive margins, underwent excision of the recurrent tumor, and remain free of disease. After median follow-up of 6.9 years (range 1 day-18 years), 5-year recurrence-free survival was 96% and overall survival (OS) of the entire cohort was 78%.

CONCLUSION

In this study of consecutive patients presenting with atypical intradermal smooth muscle neoplasm, we found good OS and local control after definitive surgical excision with negative margins, including excisional biopsy with close margins. Atypical intradermal smooth muscle neoplasm is unlikely to metastasize and has an excellent prognosis. Guidelines to determine optimal surveillance strategies for these patients should be revisited.