A malignant round cell tumour of inguinal region: a rare entity with diagnostic challenge

A. Vuagniaux, O. Gié, H. Probst

Objective

Malignant round cell tumours are a group of highly aggressive tumours, comprising Ewing sarcoma/primitive neuroectodermal tumours. The diagnostic challenge is due to the low prevalence of this group of malignancies accompanied by the poor specificity of histo-pathological findings. We present the case of a malignant undifferentiated round cell tumour of inguinal origin complicated by a bleeding cerebral metastasis.

Methods

case report

Results

We report the case of a 63-year old male presenting with a painful oedema of the left lower limb. An inguinal mass encompassing the femoral vessels was identified through CT. Duplex scanning showed occlusion of the superficial (SFV) and common femoral vein (CFV). The result of a fine needle biopsy was inconclusive. Invasion and occlusion were confirmed intra-operatively. A prosthetic bypass was interposed between the SFV and external iliac vein comprising an anastomosis of the deep femoral vein, further to an arteriovenous femoro-femoral fistula. Histo-pathologic and immunohistochemical analysis revealed a malignant undifferentiated tumour with round cells expressing CD99, and a minim reticulinic network; yet lacking the hallmark translocations t(11;22) specific to an Ewing’s sarcoma/primitive neuroectodermal tumor.

Numerous intra-abdominal and mediastinal lymph nodes metastases were identified by PET imaging further to a right frontal lobe metastasis following an acute confusional state. Regarding treatment, an adjuvant carbotaxol based chemotherapy further to neurosurgical intervention is under evaluation.

Conclusion

The round cell tumours are rare, aggressive and they should be suspected in the onset of a painless soft tissue mass. The differential diagnosis is large and relies significantly on the immunohistochemical analysis.