THE ACCURACY OF THE HISTOLOGICAL CLASSIFICATION OF LUNG-CARCINOMA ANDITS REPRODUCIBILITY - A STUDY OF 75 ARCHIVAL CASES OF ADENOSQUAMOUS CARCINOMA

The classification of lung carcinoma into a small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC), is highly reproducib le. There are few studies on the reproducibility of subtyping NSCLC, w ith anecdotal reports on the subtype of adenosquamous carcinoma. We un dertook a study of 75 cases archived as adenosquamous carcinoma. All c ases were accepted as NSCLC on independent review by three pathologist s utilizing the 1982 World Health Organization (WHO) classification cr iteria. The acceptance rate of adenosquamous carcinoma by the three pa thologists was 65%, 28%, and 65%. Cases not accepted as adenosquamous fell into the different subtypes of NSCLC, with a concordance rate bet ween each pair of pathologists of 49%, 61% and 43%, indicating poor ag reement between pathologists. The study confirms the high reproducibil ity of the classification into SCLC and NSCLC; it shows poor concordan ce for all subtypes of NSCLC with poor reproducibility of diagnosis of adenosquamous carcinoma as specified by the 1982 WHO classification. Physicians dealing with lung carcinoma should be aware of this limitat ion of classification.