High-grade, poorly differentiated breast carcinoma mimicking primary breast lymphoma: a case report of a diagnostic dilemma.

BACKGROUND

High-grade breast carcinomas can occasionally exhibit morphological and immunophenotypic features resembling hematolymphoid neoplasms, leading to diagnostic confusion. Accurate diagnosis is essential to guide appropriate therapy.

CASE PRESENTATION: We report a 35-year-old female presenting with a rapidly enlarging right breast mass. Core biopsy revealed sheets of atypical lymphoid-like cells. Immunohistochemistry (IHC) showed positivity for cytokeratin, progesterone receptor, CD10, CD117, and BCL2, while CD20, CD3, estrogen receptor, and HER2 were negative, with Ki-67 > 95%. Despite initial suspicion of primary breast lymphoma, the overall clinicopathologic correlation favored a diagnosis of high-grade, poorly differentiated invasive breast carcinoma.

DISCUSSION: This case highlights a rare diagnostic pitfall where breast carcinoma mimics lymphoma. Careful histopathologic evaluation, comprehensive IHC profiling, and clinicopathologic correlation are crucial to avoid misdiagnosis and ensure timely management.

CONCLUSION

Awareness of such mimicry can prevent unnecessary hematolymphoid-directed therapy.