Rare manifestations of tuberous sclerosis complex: low-grade oncocytic tumour and diffuse lipomatosis

Tuberous sclerosis complex (TSC) is a rare genetic disorder caused by variants in the TSC1 or TSC2 genes. This case report highlights two rare TSC manifestations: diffuse lipomatosis and low-grade oncocytic tumour (LOT), a newly recognised entity with low malignant potential.A man in his 20s presented with renal tumours and diffuse lipomatosis of his left leg since his teenage years. Over the years, numerous biopsies and scans were conducted. The renal tumours were initially classified as chromophobe renal cell carcinomas, and the patient was scheduled for a nephrectomy. After finally diagnosing the tumours as LOT, he was instead managed with everolimus.A TSC1 variant was identified. After extensive genetic testing, this variant was confirmed to cause TSC.This case highlights the phenotypic diversity of TSC, with rare manifestations like diffuse lipomatosis and LOT. Comprehensive diagnostic techniques and multidisciplinary management are essential for accurate diagnosis and treatment of the diverse presentations of TSC.