Breast spiradenoma is extremely rare, with only 4 cases reported previously. We describe an instructive case of breast spiradenoma resembling adenoid cystic carcinoma (AdCC). A 71-year-old woman underwent excisional biopsy of a breast mass after a conclusive diagnosis was unable to be obtained from core needle biopsy showing an AdCC-like pattern. Histopathologically, the lesion demonstrated solid and cribriform foci comprising basaloid cells, luminal cells, and eosinophilic hyaline material, reminiscent of solid-basaloid AdCC, alongside convoluted lumens, stromal edema, lymphocytic infiltration, and c-kit negativity. On molecular analysis, neither MYB fusion genes nor CYLD gene abnormalities were identified. These results were supportive of spiradenoma. Salivary gland– and skin adnexal–type tumors are challenging to diagnose due to morphological overlaps. This case, highlighting histopathological and molecular features, shows that breast spiradenoma can be a diagnostic pitfall among the differential diagnoses of AdCC.

乳腺螺旋腺瘤极为罕见，此前仅报道过 4 例。我们描述了一个类似腺样囊性癌 (AdCC) 的乳腺螺旋腺瘤的启发性病例。一名 71 岁的女性在无法从显示 AdCC 样模式的空心针活检中获得结论性诊断后，接受了乳房肿块切除活检。组织病理学上，病变表现为实性和筛状病灶，包括基底样细胞、管腔细胞和嗜酸性透明物质，让人联想到实性基底样 AdCC，同时伴有复杂的管腔、间质水肿、淋巴细胞浸润和 c-kit 阴性。在分子分析中，无论是MYB融合基因还是CYLD基因异常被发现。这些结果支持螺旋腺瘤。由于形态学重叠，唾液腺和皮肤附件型肿瘤的诊断具有挑战性。该病例突出了组织病理学和分子特征，表明乳腺螺旋腺瘤可能是 AdCC 鉴别诊断中的一个诊断陷阱。