Primary Mammary-Analogue Secretory Carcinoma of the Lung: A Rare Entity With an Unusual Location.

This is a case of a 55-year-old female with past medical history of tobacco smoking, hypertension, and lupus who presented with a left lung nodule, found on computed tomographic scan of the chest during workup for a recently diagnosed squamous cell carcinoma in a cervical lymph node. Resection of the lung nodule showed a 2.3-cm well-defined pale-tan mass, and histologic examination showed a well-circumscribed lesion with papillary, solid, and gland-like architectural patterns, with eosinophilic secretions, areas of comedonecrosis, and increased mitotic activity.