Abstract
<title>Abstract</title> <p>Background Malignant rhabdoid tumor (MRT) is a rare and highly aggressive malignancy of early childhood, most commonly arising in the kidney. Congenital bilateral adrenal involvement has not previously been reported. Aim We report a case of congenital bilateral adrenal MRT with extensive metastatic disease, initially misdiagnosed as advanced neuroblastoma, and rapidly complicated by fatal tumor lysis syndrome (TLS). Methods We describe the clinical presentation, diagnostic workup, treatment, and outcome of a neonate diagnosed with congenital bilateral adrenal MRT. Results A 16-day-old female neonate presented with a left lumbar subcutaneous nodule. At examination she had multiple bluish subcutaneous nodules and progressive abdominal distension. Imaging revealed bilateral adrenal masses, hepatomegaly with nodular lesions, and multiple osteolytic bone lesions. Laboratory investigations showed markedly elevated lactate dehydrogenase (LDH) levels and bone marrow infiltration by undifferentiated round cells, while urinary catecholamines were normal. A diagnosis of stage IV neuroblastoma was initially suspected. The patient rapidly deteriorated, developing brain metastases and severe tumor lysis syndrome, leading to death within a few days. Histopathological examination of a subcutaneous nodule demonstrated malignant rhabdoid tumor, confirmed by loss of INI1 expression on immunohistochemistry. Conclusion Congenital adrenal MRT is an exceptionally rare and aggressive malignancy that may closely mimic neuroblastoma in neonates. Early consideration of MRT and prompt histopathological confirmation are essential, although prognosis remains extremely poor in this age group.</p>