Pilonidal sinus involving the breast in a man: A case report and literature review.

RATIONALE Pilonidal sinus disease (PSD) involving the breast is extremely rare and has not been described in man. PATIENT CONCERNS This current case report presents a case of a pilonidal cyst in a 46-year-old man which was surgically treated. He had intermittent pain in his left breast for 2 months and came for local rupture and discharge for 1 week. DIAGNOSIS The initial diagnosis is male mastitis, on the basis of the histological features of H&E-stained specimens and immunohistochemistry of the resected lump, this case was diagnosed as PSD. INTERVENTIONS The patient underwent "enlarged resection of the left breast lesion" under local anesthesia. OUTCOMES The patient's surgical area healed well, without any signs of recurrence. CONCLUSION PSD involving the breast is extremely rare in man, with no typically clinical manifestations, and could be easily ignored. This disease requires great attentions from clinicians.