Bronchioloalveolar carcinoma presenting as chronic progressive pulmonary infiltrates in a woman with HIV: a diagnosis worth making.

A 52-year-old woman with human immunodeficiency virus (HIV) developed weight loss, cough, and breathing difficulties, accompanied by extensive bilateral pulmonary infiltrates. A lengthy infectious disease and autoimmune workup failed to reveal the etiology or produce benefit. Expert pathology review raised the possibility of pure bronchioloalveolar carcinoma. The patient was treated with erlotinib and achieved a dramatic and prolonged response to treatment. After 14 months a solitary lung nodule developed which was excised. This demonstrated an invasive adenocarcinoma with an activating epidermal growth factor receptor mutation (exon 19 deletion). As this nodule had developed in the presence of erlotinib, this deletion is only presumed to reflect the initial driver of erlotinib sensitivity. Known acquired resistance mechanisms were explored, but the lesion was negative for both exon 20 T790M gatekeeper mutations and cMET gene copy number alterations. An as yet unknown mechanism of acquired resistance is therefore assumed to be involved in this case. We discuss the diagnosis and treatment of lung cancer in HIV-positive populations and review the general and specific characteristics of bronchioloalveolar carcinoma, including response to epidermal growth factor receptor inhibitors, and known mechanisms of acquired resistance. The predilection for lung cancer in HIV-positive patients, the diffuse nature of bronchioloalveolar carcinoma that can mimic infectious etiologies and the potential for dramatic responses to therapy make this an important diagnosis to consider in this setting.