Interpretation of bone biopsies can be difficult. This biopsy contained mostly crushed bone fragments. Only a focal small area showed the lesional cells.The lesional cells are also crushed, but they appear to have monotonous oval nuclei and abundant eosinophilic cytoplasm. No pleomorphic cells. No mitoses.
Immunohistochemical Staining
Have to rule out LCH (CD1a, Langerin: negative; S100: positive in a subset of cells (nuclear and cytoplasmic)H3.3 K36M: Diffuse strong nuclear positivity in the lesional cells; H3.3 G34W: negative
Exploring Pediatric Pathology 