Malignant granular cell tumor: Clinical features and long-term survival.

Background: Malignant granular cell tumor GCT (mGCT) has not been well described. We sought to investigate associations between tumor characteristics, treatments and survival.

Methods: Patients diagnosed with mGCT years 1995-2014 were identified using the Surveillance, Epidemiology and End Results database. Descriptive statistics regarding tumor and treatment characteristics were calculated. Chi-square tests determined associations between tumor location and features. Survival analyses included Kaplan-Meier functions and Cox proportional hazard ratios (HR).

Results: Of 113 patients included, median age was 54 years and 77.0% were female. Frequent tumor sites included soft tissues (36.3%), ovary/testis (16.8%), and skin (11.5%). Median tumor size was 4.0 cm. Metastases to regional lymph nodes (12.5%) and distant sites (11.4%) occurred. Treatments included surgery (85.0%), radiotherapy (12.4%) and chemotherapy (8.9%). Overall five and 10-year cause-specific survival was 74.3% and 65.2%, respectively. Survival was worse for patients with tumors >5 cm compared to those with tumors ≤5 cm (HR = 34.03; 95% confidence interval [CI]: 2.57-450.17), and patients with metastasis (HR = 15.25; 95% CI: 1.19-195.72) compared with those without metastasis. Patients who underwent surgery had superior survival than those who did not (HR = 0.13; 95% CI: 0.05-0.34).

Conclusions: Particular tumor features and treatments are associated with superior survival. This information may be used to more accurately estimate prognosis.