• Clinical History
• Fine Needle Aspiration
• Gross Morphology
• Light Microscopy
• Electron Microscopy
• Diagnosis and Comment
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Diagnosis:

Alveolar Adenoma

Comments:

Alveolar adenoma is one type of lesion that can present as an asymptomatic, solitary peripheral nodule (SPN) on the chest radiographs of asymptomatic, older patients (1). These alveolar adenomas range in maximum dimension from 1.0 cm to 5.0 cm. The multicystic growth pattern of the alveolar adenoma simulates features of a lymphangioma and a sclerosing hemangioma of the lung. However, electron microscopy of these tumors as well as immunohistochemical studies with antibodies to apoprotein B and C of human surfactant, demonstrate that the proliferation involves neoplastic Type II pneumocytes (1, 2, 3).

DNA flow cytometric studies have shown that the neoplastic cells in the alveolar adenoma are diploid and this feature as well as the lack of mitotic activity and nuclear pleomorphism would support the concept that the alveolar adenoma is a benign tumor. Roque et al. have shown the presence of a balanced translocation between chromosomes 10 and 16 in a solitary case of alveolar adenoma (4). The clinical significance of this finding is yet to be determined. Clinical follow-up of patients with alveolar adenomas have shown no recurrence of the lesion or evidence of metastasis once the tumor is excised. Thus based on clinical observation, the alveolar adenoma should be considered a benign tumor.

CT guided FNA is a cost effective method for evaluating and planning the therapeutic approach to SPNs. The result of the FNA of this patient's alveolar adenoma yielded cells with foamy cytoplasm that were interpreted as alveolar macrophages. The alveolar macrophages in the cystic spaces of the alveolar adenoma contain surfactant as shown with immunohistochemical studies (3). Based on this data, the question could be asked as to the role of electron microscopy in further characterizing the nature of the aspirated material from this patient's alveolar adenoma.

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3.

Oliveira P, Moura Nunes JF, Clode AL, da Costa JD, Almeida MO
Alveolar adenoma of the lung: further characterization of this uncommon tumor.
Virchows Arch 1996 Oct; 429(2-3):101-108.

Koppl H, Freudenberg N, Berwanger I, Frenzer K, Bohm N.
Alveolar Adenoma of the lung. Immunohistochemical characterization of type II pneumocytes
Pathologe 1996 Mar;17(2):150-153
[German Text, English Abstract]
 

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