Histomorphology and Ultrastructure of Spontaneous Pulmonary Neoplasms in Strain A Mice

Abstract

The microscopic and ultrastructural characteristics of spontaneous pulmonary neoplasms in strain A (strA) mice are described. Fifty-one spontaneous lung tumors were identified in 34 out of 57, 11-23-month-old male strA/Hen mice. Grossly, all tumors appeared as yellow-white, discrete nodules ranging in size from 1.0-10 mm. Tumor types were randomly distributed throughout the lung; however, the right lung lobes were most frequently involved. Histologically, tumors were classified as adenoma (34/51) or carcinoma (17/51) as defined by standard histopathologic criteria. Adenomas were usually less than 4 mm in diameter and had solid (16/34), papillary (10/34), or mixed (8/34) histologic growth patterns. Carcinomas were usually greater than 4 mm in diameter and had papillary (13/17) or mixed (4/17) histologic growth patterns. Ultrastructurally, benign tumors consisted of solid or papillary areas of neoplastic type II-like cells. Cells comprising malignant tumors had varying ultrastructural characteristics ranging from well-differentiated alveolar cell types to undifferentiated cells having intracytoplasmic osmiophilic dense bodies, vacuoles, or few specialized organelles commonly observed in mature nonneoplastic pulmonary epithelial cells.

A/J Mouse As A Model For Lung Tumorigenesis Caused By Tobacco Smoke: Strengths And Weaknesses

“…Also, distant metastases to the brain or other organs are practically never observed. The histomorphology of tobacco smoke-induced lung tumors in mice was originally classified as had been done in previous studies with murine lung tumors [26]. The lesions were distinguished into focal alveolar epithelial hyperplasia, alveolar/bronchiolar adenomas, and alveolar/bronchiolar adenocarcinomas.…”

Modeling human lung cancer in mice: similarities and shortcomings

“…The more advanced tumors resemble papillary and bronchioloalveolar adenocarcinomas, and appear to metastasize infrequently (Stewart et al, 1979;Dixon et al, 1991;Foley et al, 1991).…”

Enhanced tumorigenesis and reduced transforming growth factor-? type II receptor in lung tumors from mice with reduced gene dosage of transforming growth factor-?1

“…Because A/J mice have been shown to develop spontaneous lung tumors during their lifetimes [8], AJBL6 TGF-b1 WT and HT mice that had been injected with only saline vehicle were killed after 12 mo, and the lungs were examined for lesions. Whereas 2.9% (one of 34) of WT mice had spontaneous lung lesions, 23% (six of 26) of HT mice had spontaneous lesions (data not shown).…”