Papillary neoplasm on core biopsy camouflaging high-grade invasive ductal carcinoma in a male breast: a case of histological underestimation

Abstract

Introduction: Male breast cancer (MBC) is a very rare cancer, with the prevalence being less than 1 percent of all breast cancers. Diagnostic workup is based on the same principles of triple assessment in female breast cancer. Nevertheless, certain histological subtypes, especially papillary lesions, are difficult to diagnose and are likely to be underestimated on core-needle biopsy (CNB).
Presentation Case: A 41-year-old male has been presented with a left breast mass that is locally advanced. Triple assessment showed a palpable and irregular tumor with skin involvement. Imaging revealed an area of a 38mm hypoechoic lesion with microcalcifications. Ultrasound-guided CNB showed an odd papillary neoplasm at first sight with foci of suspicion but not invasion. After a multidisciplinary discussion, a left total mastectomy was performed, and a sentinel lymph node biopsy was done on the patient.
Management and Outcome: Surprisingly, final histopathology revealed that the case was a 40mm high-grade invasive ductal carcinoma (no special type) and the invasion involved the nipple dermis and pectoral muscle, which improved the initial diagnosis dramatically. The surgical margins were bare, and the deep margin was 1mm. Sentinel nodes were negative (pN0). The tumor was positive for Estrogen Receptor (ER). As such, the patient needed a complete combination of adjuvant regimen, which included chemotherapy, post-mastectomy radiation therapy (PMRT), and endocrine therapy using Tamoxifen.
Conclusion: The case demonstrates the possibility of considerable underestimation of disease severity in male breast papillary lesions on core biopsy. It also highlights the critical need to match all elements of the triple assessment and proceed with full removal surgery if clinical suspicion remains, to facilitate proper diagnosis and stimulate appropriate multimodal adjuvant therapy.