Adjuvant radiation therapy for malignant Abrikossoff's tumor: a case report about a femoral triangle localisation.

Background: Granular cell or Abrikossoff's tumors are usually benign however rare malignant forms concern 1 to 3% of cases reported. Pelvic locations are exceptional.

Case Presentation: We report a case of a 43-years-old patient who had a benign Abrikossoff's tumor localized in the right femoral triangle diagnosed at the biopsy. The patient underwent a surgical tumorectomy and inguinal lymph nodes resection. Histologically, the tumor showed enough criteria to give diagnosis of malignancy: nuclear pleomorphism, tumor cell spindling, vesicular nuclei with large nucleoli. Moreover, five lymph nodes were metastatic. Immunohistochemistry findings confirmed the diagnosis of granular cell tumor which is positive for S100 protein and CD68 antibodies. The mitotic index was nevertheless low with a Ki67 labeling index of 1-2%. A large surgical revision with an inguinal curage following radiotherapy were decided on oncology committee. Adjuvant radiotherapy on the tumor bed and right inguinal area of ​​50 Gy in conventional fractionation was delivered with the aim of reducing local recurrence risk. There was no recurrence on longer follow-up (10 months post radiotherapy).

Conclusions: Adjuvant radiotherapy seems an appropriate therapeutic approach, even if controversial, given that some authors report effectiveness on local disease progression.