This lesion is centrally necrotic (Images 1 and 2) with abundant single spindle-like cells and infiltrative glandular structures in the periphery (Image 3). Marked infiltration by a mixed inflammatory infiltrate composed of plasma cells, lymphocytes, eosinophils, neutrophils and macrophages, was observed in a hyalinized stroma (Images 4 and 5). The spindle-like cells demonstrate mostly clear and occasionally pale eosinophilic cytoplasm and enlarged round to elongated nuclei with coarse and vesicular chromatin and occasional prominent nucleoli (Images 4, 5 and 6). These cells are intimately mixed with inflammatory cells (Images 4, 5 and 6), infiltrating a blood vessel (Image 7) and a bronchiolar wall (Image 8). Mitoses are rare. The vertebral lesion shows multiple foci of hypercellular sheets of cells characterized by abundant eosinophilic cytoplasm, pleomorphic hyperchromatic nuclei and occasional prominent nucleoli (Image 9).
The immunohistochemical profile shows: lung lesion CK7 strongly positive (Image 10), CK20 negative (Image 11), TTF focally positive (Image 12), GCDFP negative (Image 13), CD10 strongly positive (Image 14), PAS/D focal positive (Image 15), AFB and Grocott negative (Images not shown). Vertebral lesion CK7 strongly positive (Image 16), CK20 negative and TTF negative (Images not shown).