[P-13] Malignant pigmented epithelioid angiomyolipoma of the kidney in a child with tuberous sclerosis: a rare case report and literature review

Dang Anh Thu Phan1, Thuy Nhi To2 and Thi Nhu Diem Pham1

  1. Department of Pathology, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
  2. Children's Hospital 2, Ho Chi Minh City, Vietnam


Background: Pigmented epithelioid angiomyolipoma is a rare variant of epithelioid Angiomyolipoma (EAML), a part of the family of the perivascular epithelioid cell neoplasms (PEComas) with malignant potential. We reported one case of EAML occurring in the paediatric age group.

Case Presentation: A 15-year-old boy was hospitalised because of haematuria and a rapidly enlarged abdomen with a tuberous sclerosis complex (TSC) history. The CT scan revealed a large mass in the right kidney and a nodule in the left lung. The right radical nephrectomy showed a tumour of 21 cm with a yellow cut surface and huge haemorrhagic and necrosis areas. Microscopically, the tumour was characterised by epithelioid cells with high-grade atypia, large nuclei, prominent nucleoli and eosinophilic cytoplasm with scattered melanin pigment. A focal area of spindle cells around numerous vascular channels and lipomatous tissues was observed. By immunohistochemistry, the epithelioid cells were labelled for HMB45 but not for actin and the opposite of the spindle cells. Both neoplastic cells were weakly positive for CD68 and negative for synaptophysin, cytokeratin, vimentin, CD10 and EMA.

Discussion and Conclusion: TSC-associated EAML is commonly found at a younger age and shows more aggressive behaviour. With the morphology of eosinophilic to clear epithelioid cells and melanin pigment, pigment EAML should be distinguished from malignant melanoma, pigmented clear cell renal cell carcinoma, and paraganglioma. The cellular reaction with HMB-45 but no expression with cytokeratin, vimentin, S100, synaptophysin, CD68 are helpful for the diagnosis. Tumour size, nuclear atypia, mitoses, necrosis, lymphovascular invasion are critical factors for predicting behaviour.