Characterization of alkaline phosphatase cytochemistry in canine neoplastic and non‐neoplastic pulmonary mass aspirates

Abstract

AbstractBackgroundDistinguishing primary and secondary pulmonary neoplasms can be challenging via cytology, and a rapid, inexpensive diagnostic tool to differentiate these neoplasms is unavailable. Alkaline phosphatase cytochemistry (ALP‐CC) has been used to identify primary pulmonary carcinomas in human patients, and we hypothesized it could be applied to canine lung aspirates.ObjectiveWe aimed to characterize ALP‐CC expression in fine‐needle aspirate (FNA) samples of canine pulmonary neoplastic and non‐neoplastic tumors.MethodsA retrospective case search was conducted to identify cases with contemporaneous cytology and histopathology reports from pulmonary lesions, including neoplastic and non‐neoplastic etiologies. Slides prepared from pulmonary aspirates were stained for ALP‐CC activity, and the percentage of ALP‐CC‐positive primary pulmonary epithelial tumors was determined. To characterize the ALP‐CC expression in non‐neoplastic cellular constituents of pulmonary FNA samples, mesothelial cells were also evaluated.ResultsForty‐eight canine cases met the inclusion criteria. ALP‐CC–positive cells were seen in both neoplastic and non‐neoplastic lesions. In non‐neoplastic lesions, pulmonary epithelial cells were ALP‐CC positive. Eighty‐nine percent of primary pulmonary epithelial neoplasms were ALP‐CC positive, and no ALP‐CC positivity was noted in mesothelial cells. ALP‐CC–positive neoplastic cells were seen in a metastatic amelanotic melanoma.ConclusionsPrimary pulmonary epithelial neoplasms are frequently ALP‐CC positive, but such positivity is not restricted to this tumor type. Non‐neoplastic pulmonary epithelial cells can be ALP‐CC positive, whereas mesothelial cells are negative.