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30 April 2014 - Case of the Week #310

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Thanks to Dr. Raul Gonzalez, Vanderbilt University Medical Center, Tennessee (USA), for contributing this case. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.


   

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Website news:

(1) We posted updated reviews of Nonkeratinizing nasopharyngeal carcinoma - undifferentiated by Abul Ala Syed Rifat Mannan, M.D. and Songyang Yuan, M.D., Ph.D. in the Nasal cavity chapter, and Rhabdoid meningioma by Jesse Kresak, M.D. and Anthony T. Yachnis, M.D. in the CNS Tumor chapter.

(2) To the new CNS non tumor chapter, we added Herpes simplex encephalitis by Dr. Mark Cohen. To the Heart chapter, we added Noninfectious endocarditis by Dr. R. Amita.

(3) We added these topics to the Stains and Molecular Markers chapter: claudin5, an endothelial tight junction protein whose downregulation is associated with various leakage syndromes and has strong membranous expression in pancreatic solid pseudopapillary tumor, and TREM1 / CD354, which amplifies immune responses that promote pro-inflammatory cytokine production, and is associated with bacterial infection and sepsis.

(4) In the Bone chapter, we posted an updated review of Myeloma by Sheren Younes, M.D. In the Thyroid chapter, we posted updated reviews of Aplasia / Hypoplasia by Vijay Shankar, M.D. and Bethesda guidelines-diagnostic categories by Phillip A. Williams M.D., MSC and Shahidul Islam M.D., Ph.D., FRCPC.


Case of the Week #310

Clinical History:
A 49 year old woman presented with a 2 cm laryngeal mass, which was biopsied.

Micro images:



What is your diagnosis?































Diagnosis:
Low grade myofibroblastic sarcoma of the larynx

Discussion:

Immunostains were performed:

Desmin

Smooth muscle actin



Low grade myofibroblastic sarcoma, also called low grade myofibrosarcoma, is a rare, low to intermediate grade tumor composed predominantly of malignant myofibroblasts (Am J Surg Pathol 1998;22:1228). It typically occurs in the head and neck (tongue and oral cavity) and extremities, and rarely in the mesentery and the pelvic peritoneum (J Clin Pathol 2008;61:301). Several cases have recently been reported in the larynx (J Cancer Res Ther 2013;9:284, J Int Med Res 2011;39:311, Int J Surg Pathol 2011;19:822).

Microscopically, it is circumscribed to diffusely infiltrative with fascicles or storiform growth of spindled tumor cells. Cells have ill defined, pale eosinophilic cytoplasm, fusiform nuclei that are either elongated or wavy with evenly distributed chromatin or round and vesicular with indentations and small nucleoli. There is usually at least focal nuclear atypia with hyperchromasia and irregular nuclear membranes. The stroma is collagenous with prominent hyalinization, and numerous thin walled capillaries may be present. There are no histiocytic giant cells, or prominent inflammation. Mitotic activity is 1-6 mitoses/10 HPF. Immunostains are helpful for diagnosis. At least one myogenic marker is positive, and tumor cells are negative for h-caldesmon. Electron microscopy shows myofibroblastic features of indented and clefted nuclei, variable rough endoplasmic reticulum, discontinuous basal lamina and fibronexus junctions (Ultrastruct Pathol 2008;32:97, Int J Surg Pathol 2013;21:29).

The differential diagnosis is broad, and includes numerous neoplastic fibroblastic and myofibroblastic lesions, as discussed in the topic, as well as nodular fasciitis. It is not an ALK+ tumor, unlike inflammatory myofibroblastic tumor (Hum Pathol 2008;39:846).

After excision, low grade myofibroblastic sarcoma commonly recurs, but only rarely metastasizes.

Nat Pernick, M.D., President
and Palak Thakore, Associate Medical Editor
PathologyOutlines.com, Inc.
30100 Telegraph Road, Suite 408
Bingham Farms, Michigan (USA) 48025
Telephone: 248/646-0325
Email: NatPernick@Hotmail.com
Alternate email: NatPernick@gmail.com