ABSTRACT Background and Objectives The prognostic differences between subcutaneous leiomyosarcoma and dermal leiomyosarcoma are not well defined due to limited cohort sizes and insufficient follow‐up in prior studies. This study aimed to investigate the clinicopathological features of subcutaneous and dermal leiomyosarcoma and estimate their 10‐year rates of metastasis, local recurrence, and overall survival. Additionally, we propose standardized follow‐up recommendations. Methods All patients diagnosed with cutaneous leiomyosarcoma in Denmark from 1980 to 2022 were included. The prognosis was estimated using age‐ and sex‐standardized stratified cause‐specific Cox‐regression with all‐cause mortality as competing risk. Results We included 196 patients with subcutaneous leiomyosarcoma and 465 with dermal leiomyosarcoma. The 10‐year local recurrence rate was similar in patients with subcutaneous leiomyosarcoma (15%) and dermal leiomyosarcoma (11%, p = 0.13). However, patients with subcutaneous leiomyosarcoma had a significantly higher 10‐year risk of metastasis (25%), primarily observed in grade 2 and 3 tumors, compared with dermal leiomyosarcoma (2.7%), p < 0.001, and a lower 10‐year‐overall survival (56% vs. 64%), p = 0.02. Conclusions Grade 2 and 3 subcutaneous leiomyosarcoma should be classified as a high‐risk sarcoma with a substantial risk of metastasis and poor overall survival, necessitating follow‐up that includes both clinical examinations and PET/CT or CT of the thorax for 5 years to detect both locoregional and distant metastases. Dermal leiomyosarcoma should be considered a low‐risk sarcoma due to its low risk of metastasis and moderate risk of local recurrence, suggesting that the follow‐up can focus on clinical examinations for 4 years as the 10‐year risk of local recurrence is < 1% after this time point.
Abebe et al. (Thu,) studied this question.
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