Intractable Rare Dis Res. 2025;14(2):145-147. (DOI: 10.5582/irdr.2025.01018)

Primary rectal malignant melanoma with schistosomiasis

Cheng ZM, Wang C, Cai YL

Primary rectal malignant melanoma with schistosomiasis is extremely rare. To date, only a few cases have been reported in the literature. Due to its high mortality rate, most patients with rectal malignant melanoma die within five years of diagnosis. However, the etiology and optimal treatment strategies remain controversial. A 79-year-old female patient presented with intermittent hematochezia for 2 months. Digital rectal examination, computed tomography (CT) scan, and colonoscopy revealed a fleshy mass measuring 3 cm in diameter in the rectum. A biopsy confirmed a preoperative diagnosis of malignant melanoma of the rectum, and a radical rectal resection was performed. Histopathological examination of the surgical specimen confirmed malignant melanoma, and numerous Schistosoma japonicum organisms were identified within the tumor. The patient subsequently received Dabrafenib and Trametinib therapy and remained disease-free for 5 years postoperatively, with no evidence of recurrence. This case highlights the potential treatment strategies for this rare carcinoma and underscores the need for further investigation into the relationship between schistosomiasis and melanoma.

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