Melanotrichoblastoma misdiagnosed as basal cell carcinoma: a case report

Background: Melanotrichoblastoma (MTB) is an exceptionally rare benign adnexal tumor with follicular differentiation. Its clinical and dermoscopic resemblance to pigmented basal cell carcinoma (BCC) often leads to misdiagnosis. Case presentation: A 51-year-old male presented with a slow-growing, blue-black nodule on the right canthus that had been present for five decades, with recent central ulceration. Dermoscopy revealed homogeneous pigmentation with atypical blue-white areas and dilated vessels, suggestive of BCC. Histopathological examination showed well-demarcated dermal nests of basaloid cells with peripheral palisading and stromal pigment deposition. Importantly, retraction clefts were absent, a key feature distinguishing MTB from BCC. The lesion was completely excised, with no recurrence after two years. Conclusion: This case highlights the diagnostic challenge of MTB. Histopathology remains the gold standard for differentiation, wherein the absence of retraction clefts serves as a pivotal diagnostic clue. Increased awareness of MTB is essential to avoid misdiagnosis and ensure appropriate, conservative management.