Adenosquamous carcinoma of the lung: radiologic appearance.
OBJECTIVE
To our knowledge, the imaging features of pulmonary adenosquamous carcinoma, a form of bronchogenic carcinoma with a greater propensity for metastases at the time of diagnosis and a poorer prognosis than other forms of bronchogenic carcinoma, have not been reported. Accordingly, we studied the radiologic appearance of this tumor to describe the findings and discern if there are features that distinguish it from other bronchogenic carcinomas.


METHODS
Clinical and radiologic features of 30 cases of adenosquamous carcinoma were reviewed. Chest radiographs were available in all cases and CT scans were available in 23. In cases without CT scans, planar tomograms were reviewed in five cases and MR images were reviewed in one. Tumors were defined by location, morphology, and TNM classification.


RESULTS
The tumors measured 0.6-6.5 cm in diameter (mean, 2.8 cm) on CT scans or chest radiographs. One tumor not seen even in retrospect on CT scans or chest radiographs was found at autopsy. Twenty-five tumors were solid and four were cavitary. Five tumors were central and 25 were peripheral, including one tumor of the superior sulcus of the lung and the tumor not seen at imaging. Tumor margins were poorly defined in 19 and spiculated in 10. Four large masses had heterogeneous attenuation on CT scans; one had punctate calcification. Fifty-three percent of tumors were peripheral nodules 1-3 cm in diameter. Results of fine-needle aspiration of 18 masses indicated malignant tumors in 16 cases, but adenosquamous carcinoma in only two. Evidence of previous lung injury, including tumor in or next to scar, pneumoconiosis, radiation fibrosis, and interstitial fibrosis, was found on CT scans, chest radiographs, and/or pathology in half the patients.


CONCLUSIONS
The radiologic findings of adenosquamous lung carcinoma are a spectrum, typically a peripheral solitary nodule, less commonly a central hilar mass or tumor of the superior sulcus. Scar or fibrosis within the lungs suggests that adenosquamous carcinoma, just as adenocarcinoma, may arise in scarred lung parenchyma.
Department of Radiology, University of Michigan Hospitals, Ann Arbor 48109-0326.
E A
EA
Kazerooni
M
M
Bhalla
J A
JA
Shepard
T C
TC
McLoud
D000368:Aged; D018196:Carcinoma, Adenosquamous / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D014057:Tomography, X-Ray Computed