Brief ReportSpiradenoma With Adenoid Cystic Carcinoma–Like FeaturesHopkins, Christina BS*; Moyer, Amanda MD†; Huttenbach, Yve Thaller MD†Author Information *School of Medicine, Baylor College of Medicine, Houston, TX; and †Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX. Correspondence: Christina Hopkins, BS, Baylor College of Medicine, One Baylor Plaza, BCM 315, Houston, TX 77030 (e-mail: email@example.com). The authors declare no conflicts of interest. Online date: December 17, 2019 The American Journal of Dermatopathology: June 2020 - Volume 42 - Issue 6 - p 442-445 doi: 10.1097/DAD.0000000000001594 Buy Metrics Abstract Spiradenoma is a benign cutaneous adnexal neoplasm that characteristically presents as a painful dermal nodule, often on the head or trunk. It has a distinct histologic phenotype and management involves surgical excision with low risk of recurrence. In comparison, adenoid cystic carcinoma (ACC) is a low-grade malignancy manifesting as an often painless subcutaneous mass with potential for local invasion, perineural extension, and high rates of recurrence after excision. We report the case of a 63-year-old male patient with a recurrent, painful hematoma-like cyst overlying the left lower extremity tibial tuberosity. A firm nodule was located at the base of the cyst, which was histologically consistent with spiradenoma. Interestingly, the lesion contained multifocal ACC-like components composed of epithelial basaloid cells surrounding pseudocystic structures filled with mucinous material. The ACC-like components did not demonstrate infiltration or perineural invasion. To the best of our knowledge, this is the second publication in the English literature regarding spiradenoma with an ACC-like pattern. Although a benign entity, knowledge of this morphological variant of spiradenoma is essential for diagnostic accuracy in these cases. If a limited biopsy captures only the ACC-like component of a spiradenoma, the lesion may be incorrectly diagnosed as ACC. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.