Background <p>Aggressive angiomyxoma is a rare, locally invasive soft tissue tumor that predominantly affects women. It typically arises in the pelvic and perineal regions, with male cases being exceptionally rare. Despite its benign classification, its infiltrative nature and high recurrence risk make early diagnosis and management crucial.</p> Aim of the work <p>This report presents a rare case of aggressive angiomyxoma in a young male patient with extensive abdominal involvement. We aim to highlight the importance of considering this tumor in the differential diagnosis of deep-seated pelvic masses and discuss the role of imaging and surgical management.</p> Case presentation <p>A 30-year-old man presented with progressive right gluteal swelling, abdominal pain, and chronic constipation. Physical examination revealed gluteal asymmetry and a firm mass on rectal examination. Magnetic resonance imaging (MRI) showed a large, heterogeneous tumor extending from the ischioanal fossa through the pelvic floor, compressing the rectum. Multiple cystic structures were observed in the abdomen, compressing the bladder and right ureter, leading to hydronephrosis. The tumor exhibited a characteristic swirling and laminated pattern on T2-weighted image (T2WI). Given its extensive infiltration, the patient underwent pelvic exenteration with end colostomy. Histopathological analysis confirmed the diagnosis, showing spindle-shaped cells within a myxoid stroma, positive for vimentin and CD34, with a low Ki-67 proliferation index.</p> Conclusions <p>This case highlights an unusual presentation of aggressive angiomyxoma in a male patient, with rare abdominal extension and cystic involvement. MRI played a key role in diagnosis and surgical planning. Despite its benign nature, the high recurrence risk necessitates long-term follow-up. Documenting such rare cases expands the understanding of aggressive angiomyxoma and underscores the importance of including it in the differential diagnosis of pelvic masses in both genders.</p>