Invasive Breast Carcinoma Arising in Microglandular Adenosis: Two Case Reports
Case 2 was a 57-year-old woman with a palpable mass in her right breast. No other symptoms were associated with the mass. On physical examination, a firm, movable mass measuring approximately 3 cm was palpable at the right upper outer quadrant of the breast. Nipple retraction was observed. She had no medical or familial history of cancer. Mammography revealed a huge mass-like lesion at the right upper breast and ultrasound revealed a lobulating heterogeneous hypoechoic mass measuring 2.6×2.2 cm at the 11 o'clock region of the right breast (). Positron emission tomography revealed fluorodeoxyglucose (FDG) uptake at a 2.7 cm hypermetabolic mass in the upper outer quadrant of the right breast (SUVmax: 15.4) and FDG uptake in lymph nodes of the right axilla (level 1). A core needle biopsy of the lesion suggested invasive carcinoma and encapsulated papillary carcinoma. The patient underwent right MRM with SLNB. A well-demarcated solid mass measuring 2.8×2.4 cm was found on gross examination (). Microscopic examination revealed encapsulated papillary carcinoma arising in MGA, which exhibited atypia and variable proliferation (approximately 5.2 cm in the largest dimension). Most areas of the MGA were atypical and were lined by large pleomorphic cells with nuclear hyperchromasia and prominent nucleoli. A 0.3×0.25 cm focus of invasion was associated with an altered chondromyxoid stroma adjacent to the encapsulated papillary carcinoma. Typical MGA tubules with intraluminal colloid-like secretory material were found at the more peripheral area of the lesion (). IHC staining revealed the followings: S-100 protein (+), smooth muscle myosin-heavy chain (-), ER (-), and PR (-). No metastasis was observed in the sentinel lymph nodes. The final diagnosis was invasive ductal carcinoma (grade 2) associated with encapsulated papillary carcinoma arising in MGA with stage IA, T1 (0.3×0.25 cm), N0 (0/5), M0, and lymphovascular invasion (-). The patient showed no evidence of recurrence on medical follow-up at 19 months. We consulted Dr. Fattaneh Tavassoli, a breast pathologist at the Yale School of Medicine, USA, about these two cases.