23 September 2008 – Case of the Week #130
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We have split the chapter on Skin tumors into separate chapters for Melanocytic and Non-melanocytic tumors, and are currently updating the Melanocytic tumors chapter.
We thank Drs. Mona Kandil, Moshera Abdel Wahed and Rehab Samaka, from Menofiya University, Egypt, for contributing this case. To contribute a Case of the Week, email [email protected] with the clinical history, your diagnosis and diagnostic microscopic images in JPG, GIF or TIFF format (send as attachments, we will shrink if necessary). Please include any other images (gross, immunostains, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you $35 (US dollars) by check or PayPal for your time after we send out the case. Please only send cases with high quality images and a diagnosis that is somewhat unusual (or a case with unusual features).
Case of the Week #130
A 27 year old woman presented with painful swelling in the fibula. There was a history of an aneurysmal bone cell 5 years previously. Xrays showed a punched-out, lytic, intramedullary lesion in the distal fibula (#1; #2). There was no sclerotic rim or periosteal reaction. A segment of fibula was excised.
Gross image: #1
What is your diagnosis?
Myeloid (granulocytic) sarcoma
Myeloid sarcoma is also called granulocytic sarcoma, extramedullary myeloid tumor or chloroma. It presents as a mass lesion, usually associated with AML M4 or M5 or a chromic myeloproliferative syndrome, although rarely no leukemia or myelodysplasia is identified in blood or bone marrow (J Neurosurg 2006;105:916). At all sites combined, it is found in 2-8% of AML patients.
The morphology of the leukemic infiltrates resembles the underlying disease. Myeloid tumors may be (a) blastic, with myeloblasts containing a mild/moderate rim of basophilic cytoplasm, fine nuclear chromatin and 2-4 nucleoli; (b) immature with myeloblasts, promyelocytes and eosinophilic myelocytes; or (c) differentiated with promyelocytes, eosinophilic myelocytes and more mature forms.
Myeloid sarcoma is often misdiagnosed. Immunostains are necessary to differentiate these tumors from lymphoma. All tumors are typically immunoreactive for lysozyme and CD43. Myeloid tumors are commonly immunoreactive for myeloperoxidase and CD117 (Archives 2001;125:1448). Monocytic tumors are typically immunoreactive for CD68 and CD163 (Diagn Pathol 2007;2:42). Tumor cells may express CD45/LCA, but are typically negative for CD3, CD20 and CD79a.
Additional references: Leukemia-Acute chapter of PathologyOutlines.com.
Nat Pernick, M.D., President
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