Reasons for rarity of anal melanocytic naevi

Melanocytic nevus of the anal canal and granular cell tumor of the cecum: a case report and literature review of 2 coincidentally co-occurring neurocristopathies

Granular cell tumors are predominantly benign soft tissue tumors originating from Schwann cells, whereas melanocytic nevi are benign proliferations of melanocytes. We present the case of a patient with the presence of both entities located in the cecum and anal canal, respectively, constituting an extremely rare coincidental finding. A 43-year-old woman was evaluated by colonoscopy for iron-deficiency microcytic anemia that had lasted for 1 year. Colonoscopy demonstrated a macular lesion of 0.3 cm with a melanocytic appearance in the anal canal; at the cecum level, a subepithelial, yellowish, and partially mobile firm nodular lesion measuring 1.3 cm was observed. A histopathological study showed a melanocytic nevus in the anal canal and a granular cell tumor in the cecum. This is the first reported case of a patient with the extremely rare coincidental-incidental finding of these 2 entities at the same time.