Track: Case Reports

Abstract:

Lactating adenomas in extramammary sites are exceptionally rare, typically occurring along the embryonic mammary ridge or in anogenital mammary-like glands. Ectopic breast tissue and anogenital mammary-like glands can develop the full spectrum of mammary pathology, including hormonally responsive tumors during pregnancy and lactation. We present a case of a 26-year-old woman who developed a rapidly enlarging 12 cm lactating adenoma within her cesarean section scar during her second pregnancy. The mass was noted at term and had progressively enlarged throughout gestation without significant pain. During repeat cesarean delivery, complete excision was performed. The diagnosis was confirmed with immunohistochemical staining. This case was distinguished by the tumor's unprecedented location in surgical scar tissue and its exceptional size, representing the largest ectopic lactating adenoma reported to date to our knowledge. The unique presentation suggests either embryonic mammary remnants coincidentally positioned along the surgical path or iatrogenic transplantation during previous surgery. This case underscores the importance of considering ectopic mammary tumors in the differential diagnosis of abdominal wall masses, particularly in pregnant or postpartum patients, even in scar tissue where such lesions have not been previously documented. We review all prior reports of ectopic lactating adenomas and discuss the diagnostic challenges for dermatopathologists encountering this rare entity.

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Arjun Bashyam