| Histology shows multiple fragmented needle core biopsies of tumour infiltrating fibrofatty |
| connective tissue. The tumour is composed of sheets of medium-sized to large atypical cells with |
| vesicular nuclei, prominent central single nucleoli and relatively abundant eosinophilic cytoplasm |
| and their admixed small lymphocytes and scattered histiocytes. |
| |
| An extensive panel of immunohistochemical stains has been performed. The neoplastic cells do |
| not express cytokeratin cocktail, cytokeratin 5/6, EMA or WT1. Occasional cells show nuclear |
| staining for S-100. Reactive lymphoid cells are highlighted by immunostaining for CD2, CD3, CD20 |
| and CD79a, but the tumour cells are negative. They show weak trace of focal staining for CD56. |
| They do not express CD138, CD30, CD8, chromogranin, ALK, HHV-8 or granzyme B. Many of the |
| tumour cells show patchy positivity for CD4, CD14 and CD45 and many are CD68-positive. |
| Scattered cells are CD117-positive while most are CD43-positive and many are CD34-positive. Some |
| cells are CD15-positive. Scattered TdT-positive cells are identified. The Ki67 proliferation fraction is |
| variable, up to 50% in some areas. |
| |
| The morphological appearances and immunophenotype are most in keeping with myeloid |
| sarcoma. Referral to haematology is recommended. |
