Anterior Nasal Septal Angiomyolipoma Mimicking a Dermoid: A Case Report and Updated Review of an Evolving Sinonasal Entity

Angiomyolipoma (AML) of the nasal cavity is an uncommon mesenchymal lesion that differs from classic renal and hepatic AML in several clinicopathologic features.We report a 51-year-old man with diabetes mellitus, hypertension, and dyslipidemia who presented with intermittent external nasal swelling and concern about nasal contour, without nasal obstruction or chronic inflammatory sinonasal symptoms.Examination showed a soft, compressible, non-tender anterior nasal lesion.Non-contrast axial computed tomography and magnetic resonance imaging demonstrated a well-defined approximately 2.1 × 2.0 cm lesion in the left anterior nasal cavity/nostril, with a high T2 signal, an internal fatty component, and heterogeneous enhancement, causing displacement of the cartilaginous septum.A dermoid was favored radiologically.The patient underwent septoplasty with excision of the mass in March 2023.Histopathology showed AML with mature adipose tissue, thick-walled vessels, and bland smooth-muscle cells; smooth muscle actin was positive and HMB-45 was negative.Recovery was uncomplicated, with no residual or recurrent lesion on available follow-up.This case highlights an unusual anterior septal location and a radiologic mimic.Recent immunophenotypic and molecular data suggest that many sinonasal lesions historically termed AML are better classified as sinonasal angioleiomyoma with adipocytic differentiation.