Details
67 year old female with a CT diagnosis of 3.0 cm cavitary pulmonary mass. This is a wedge resection from that “mass”.
Adenocarcinoma of the lung is characterized by the presence of malignant glandular epithelial cells. In this slide, foci of atypical glandular formation are found in the background of densely fibrotic lung parenchyma with inflammation. Approach to such cases can be difficult given the fibrotic background and considerable inflammation, which can often cause cytologic atypia. In this case, haphazardly-shaped glands with significant cytologic atypia should prompt suspicion and further workup. Immunostaining such as CK7, Napsin A, TTF1 may help to differentiate adenocarcinoma from squamous cell carcinoma (CK5/6, p63, p40).
In the case of adenosquamous carcinoma that is often associated with scarring, a cut-off of 10 % of each component (adeno and squamous) must be fulfilled by histomorphology.
A proper work up with imaging correlation and immunohistochemistry to ensure lung origin versus metastases from elsewhere (breast, prostate, gastrointestinal, kidney, etc) should be done.
Biomarker testing for EGFR, ALK, ROS1, RET, KRAS, BRAF, HER2, MET should be considered for further management.