Discussion 2: Central necrosis and calcifications are common, mimicking high grade DCIS. Loss of E-Cadherin expression confirms the lobular phenotype. p120 shows cytoplasmic staining.

Discussion 1: Pleomorphic LCIS is a variant of LCIS, characterized by large dyscohesive cells with marked nuclear pleomorphism, >4 times the size of a lymphocyte, equivalent to the cells of high-grade DCIS.

Diagnosis: Lobular carcinoma in situ (LCIS), pleomorphic type

Discussion 2: This is always secondary to something external to the lung, usually in the mediastinum or in the heart. In this case, being from St. Louis, he probably had histoplasmosis and developed sclerosing mediastinitis which led pulmonary vein compression and then venous infarction in the lung.

Discussion 1: The lung shows an infarct with minimal blood closely associated with a pulmonary vein. This is characteristic of a venous (as opposed to arterial) infarct. This is always secondary to something external to the lung, usually in the mediastinum or in the heart.

Diagnosis: Venous infarction in the setting of mediastinal disease (probably sclerosing mediastinitis due to histoplasmosis).

Imaging showed lower lobe pulmonary infiltrates and mediastinal soft tissue expansion associated with flecks of calcification and compression of pulmonary veins. He underwent lung biopsy. Image B is elastic trichrome stain.