Alveol�res Adenom der Lunge Immunhistochemische Charakterisierung von Pneumozyten Typ II

Abstract

The alveolar adenoma of the lung is a rare benign tumor in which the normal parenchymal architecture is imitated by a proliferation of both the alveolar epithelial cells and the mesenchymal septal cells. The first description, based on six cases, was published in 1986 by Yousem and Hochholzer. From their ultrastructural findings they presumed a type II pneumocytes differentiation of the epithelial cells. We investigated an alveolar adenoma of the lung immunohistochemical by means of antibodies against apoprotein B and C of human surfactant. Both the lining cells and the macrophages in the alveolar-like spaces were stained. The septal connection tissue cells did not react. These findings confirm the expression of surfactant constituents and, hence, the differentiation into type II pneumocytes of the epithelial cells of the alveolar adenoma.

Peripheral papillary tumor of type-II pneumocytes: a rare neoplasm of undetermined malignant potential

“…Our immunohistochemical observations confirm the differentiation toward type-II pneumocytes. The derivation of the tumor from type-II pneumocytes, supported by many authors [3,9,10,12,13,19], is confirmed by us for the following reasons:…”

“…The differential diagnosis includes entities such as alveolar adenoma, solitary bronchioloalveolar adenocarcinoma, atypical adenomatous hyperplasia, micronodular pneumocyte hyperplasia, sclerosing hemangioma, and the "pulmonary tumor resembling fetal lung". The presence of a fibrous capsule and the absence of a cystic or cribriform pattern distinguishes it from the alveolar adenoma [9] first described by Yousem and Hochholzer [20]. The absence of marked nuclear atypia with fairly uniform round nuclei lining the papillary formations, the presence of a complete or partial fibrous capsule, and the expansive nodular growth with compression of the surrounding lung parenchyma distinguish the papillary tumor from the solitary bronchioloalveolar adenocarcinoma, which is characterized by a lepidic pattern of growth.…”

“…Since then, eight additional cases have been reported in the English literature showing immunohistochemical and ultrastructural evidence of differentiation toward type-II pneumocytes [2,3,6,10,12,13,19]. Most of these reports and the AFIP atlas on tumors of the lower respiratory tract [1] consider papillary adenoma of type-II pneumocytes a benign lesion distinct from alveolar adenoma, another rare entity also composed of type-II pneumocytes [9,20]. However, Mori et al [12] have challenged this dominant view on the basis of a case that showed histological and cytological features of a low-grade malignancy.…”

An unusual case of a microscopic alveolar adenoma coexisting with lung carcinoma: a case report and review of the literature

“…Most of the cases are asymptomatic [4], and a few of the patients have symptoms that are unrelated to the lesion or are pleuritic in nature. These lesions have unknown growth potential and are usually stable over a long period of time; only one case showed 20% growth during an 8-month follow-up period [11]. …”