23 September 2008 – Case of the Week #130


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23rd Annual Park City Surgical Pathology Workshop


This 20-hour workshop is designed for the pathologist, clinician, and oncology specialist, focusing on surgical pathology, cytopathology, and hematopoietic pathology.


Short lectures and case-oriented discussions will include in-depth reviews of diagnostic anatomic pathology, insight into difficult differential diagnoses, use of immunohistochemistry and new technology to improve diagnosis.



Participants at the 23rd Annual Surgical Pathology Workshop will be asked to examine microscopic images and formulate a diagnosis and patient management strategy.  The faculty pathologist will then discuss the diagnosis, differential diagnosis, patient management, and other pertinent features.  Cases will be selected to represent common and/or difficult diagnostic problems.  Held at The Canyons in Park City, Utah.  Click here for our website.




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 NatPernick@Hotmail.com 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


Clinical History


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


Micro images: #1#2#3#4


What is your diagnosis?




























Myeloid (granulocytic) sarcoma




Special stains showed diffuse immunoreactivity for CD45/LCA, and focal reactivity for CD45RO, CD3 and CD34.  A CD20 stain was negative.  A myeloperoxidase stain (not available) was also positive. 


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.


Aggressive treatment, including bone marrow transplantation, is recommended (Leukemia 2007;21:340, Cancer 2002;94:1739).


Additional references: Leukemia-Acute chapter of PathologyOutlines.com.



Nat Pernick, M.D., President
PathologyOutlines.com, Inc.

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