23 July 2009 – Case of the Week #153
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Thanks to Dr. Mowafak Hamodat, Eastern Health of Newfoundland and Labrador, St. John's, Canada, for contributing this case. To contribute a Case of the Week, email NatPernick@Hotmail.com with the clinical history, your diagnosis and high quality microscopic images (see www.webpathology.com for examples) 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 (see www.webpathology.com for examples) and a diagnosis that is somewhat unusual (or a case with unusual features).
Case of the Week #153
A 34-year-old woman presented with a history of indurated papular lesions on her hands and face. The lesions were red-blue and located around the nail folds, on the dorsum of the fingers and around the mucosal surface on her face.
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PAS low power PAS high power
What is your diagnosis?
Multicentric reticulohistiocytosis (MRH) is a rare disorder of histiocytes (Am J Surg Pathol 1990;14:687) associated with destructive arthritis. In 28% of cases, it presents with a neoplasm, and when malignancy is present, MRH precedes the development of cancer in 73% of cases (Med Pediatr Oncol 1985;13:273). MRH may be a paraneoplastic process (J Am Acad Dermatol 1998;39:864), or the association may be simply due to reporting bias (eMedicine).
Multicentric reticulohistiocytosis typically affects women 40-50 years, but it has also been diagnosed in a 6 year old girl (J Rheumatol 1998;25:794). It is characterized by skin lesions on the hands (clinical image), especially at the base of the nails. Lesions may also appear on the face, ears, arms, scalp or mucosal surfaces. The lesions vary from small papules to lesions several centimeters across, and are usually skin colored, yellow or red-brown.
On histologic examination, there are prominent oncocytic histiocytes and multinucleated giant cells, which have eosinophilic, “ground-glass” cytoplasm (Dermatology 2007;214:268, Clin Exp Dermatol 2004;29:373). The histiocytes and giant cells are positive for vimentin, CD68, CD45 and PAS, as well as CD163 and lysozyme. They are negative for S100, desmin, muscle-specific actin, and CD34 (J Eur Acad Dermatol Venereol 2001;15:524, Skinmed 2004;4:71). These findings are similar to those in solitary reticulohistiocytoma (Am J Surg Pathol 2006;30:521).
The differential diagnosis includes these other histiocytic disorders, which usually have a different clinical presentation:
• Epithelioid fibrous histiocytoma - usually < 1 cm on extremities, usually no giant cells, primarily myofibroblastic, not histiocytic
• Epithelioid sarcoma - deep seated tumor with markedly atypical cells that form granuloma-like clusters with central necrosis; tumor cells are EMA+, keratin+, CD68-
• Granulomatous inflammation - well formed granulomas and prominent lymphocytes, no large epithelioid histiocytes with eosinophilic glassy cytoplasm
• Histiocytic sarcoma - typically forms a large mass of epithelioid histiocytes with significant nuclear atypia and mitotic activity
• Juvenile xanthogranuloma - usually children, has scattered Touton-type histiocytic giant cells and numerous eosinophils, but large epithelioid histiocytes are not prominent
• Rosai-Dorfman disease - associated with adenopathy; histiocytes are pleomorphic and S100+, and are associated with emperipolesis, B cells and plasma cells
There is no consistently reliable treatment, although TNF inhibitors (Arch Dermatol 2008;144:1360), aminobisphosphonates (Arthritis Rheum 2003;48:3538) and immunosuppressive drugs (Dermatol Online J 2009;15:2) have been effective in individual cases, but not consistently (Ryumachi 1993;33:68).
Nat Pernick, M.D., President and
Kara Hamilton, M.S., Assistant Medical Editor
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