Primary metaplastic breast carcinoma or breast metastasis of a poorly differentiated squamous cell carcinoma from the lung? Distinction not always clear

Diagnosing primary triple-negative breast cancer (TNBC) with lung metastases or primary TTF1negative lung carcinoma can be difficult due to lack of a TNBC standard immunoprofile.We report a rare case of a woman with an age range between 50 and 55 years, who presented with a mass of the left breast evolving for 2 months. The core needle biopsy concluded to a TNBC. Complete staging with a thoraco-abdomino-pelvic and cerebral computed tomography revealed a huge lung mass associated with laterotracheal and subcarineal adenomegaly next to spinal lytic lesions and bilateral adrenal masses consisting with metastasis. The lung biopsy revealed a poorly differentiated squamous cell carcinoma. The patient was then scheduled to chemotherapy.Pathological and immunohistochemistry studies are limited to establish the formal diagnosis between primary metaplastic carcinoma that metastasize to the lung and primary lung poorly differentiated squamous cell carcinoma. Confrontation with radiology and clinical presentation is highly important to resolve the problem. (c) 2023 SESPM. Published by Elsevier Espana, S.L.U. All rights reserved.

Automated summary

Diagnosing primary triple-negative breast cancer with lung metastases or primary TTF1negative lung carcinoma can be difficult due to lack of a TNBC standard immunoprofile. We report a rare case of a woman with a lung squamous cell carcinoma diagnosis confirmed through confrontation with radiology and clinical presentation.