S13C4P2-3: Characteristic histiocytes of histiocytosis X are present in the dermal infiltrates. Focally, they have collected in the overlying epidermis. Near the bottom of the field, there are several cells with thin, elongated nuclei and scanty cytoplasm; these cells are migratory histiocytes.

S13C4P2-4: This is an inflamed, polypoid lesion of the axilla. It is broadly papillary at the surface  and the stalk has been cut across near the bottom of the field. There are spotty infiltrates of lymphoid cells in the fibrous stalk. A green arrow points to a rounded defect in the epidermis. As seen in the next photomicrograph, the defects contains histiocytes.

S13C4P2-5: At higher magnification, the cells of the defect show the characteristic cytologic features of the cells of the infiltrates of histiocytosis X. Some of the nuclei are deeply grooved or notched (green arrows).

S13C4P2-6: Somewhat atypical histiocytes form spotty, loose infiltrates in the fibrous stalk. This localized lesion can be accommodated in the concept of histiocytosis X, as an example of eosinophilic granuloma.