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30 March 2011 – Case of the Week #201
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Thanks to Alejandro Martínez Vázquez, Campeche, Mexico, for contributing this case. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.
(1) Thanks to Michael Constantinescu, M.D., Overton Brooks VA Medical Center, Louisiana, for writing a new section for the Thyroid Gland chapter on Bethesda Guidelines for Cytology. Thanks to Dr. Larry Bernstein, Triplex Consulting, Connecticut, for writing Cardiac topics for the Clinical Chemistry chapter.
(2) We recently posted two articles on our Management Page: Déjŕ vu all Over Again, by Mick Raich, Vachette Pathology, click here, and Stories That Will Curl Your Hair… Or Close To It!, by Michelle Miller, Vachette Pathology, click here.
(3) Our jobs page now lists jobs by specialty, beginning March 1, 2011. The specialty "tags" are based on the content of the ad - please be aware that most jobs only describe the position in general - you may need cytopathology experience even if not indicated in the ad. The links are after "other countries" near the top of the page.
Case of the Week #201
A 12 year old Latin American boy presented with a subcutaneous mass of the right malar area that had evolved over two years. There were no systemic symptoms, and only mild local tenderness.
Grossly, the tumor was 1.5 cm and not encapsulated / not well delimited. It was soft, fatty and did not invade the parotid duct or other adjacent structures.
What is your diagnosis?
Rhabdomyomatous mesenchymal hamartoma
Mesenchymal hamartoma is an uncommon lesion, often in the chest wall or liver, containing disordered mature elements, including adipose tissue, nerve bundles, collagen or bile ducts (Radiology 2002;222:205). Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare dermal or subcutaneous lesion comprised of disordered mature adipose tissue, skeletal muscle, adnexal elements, nerve bundles, collagen, and in this case, capillary vessels (J Cutan Pathol 2002;29:238).
Most cases have been described in young patients on the head and neck (Actas Dermosifiliogr 2008;99:474). This entity exists under various names including striated muscle hamartoma, congenital midline hamartoma, and hamartoma of cutaneous adnexa and mesenchyme. There is no evidence of cellular or malignant degeneration. While the etiology of RMH is unknown, possible explanations include aberrancy in the embryonic migration of mesodermally derived tissues or a genetic defect predisposing to the formation of hamartomas. Although an association with congenital abnormalities is uncommon, this possibility should be assessed by the clinician. There are a few cases reported in the perianal area, vagina and digits (J Cutan Pathol 2002;36:61).
These tumors are benign, and are typically only excised if causing mass type effects or for cosmetic reasons.
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and Liz Parker, B.A., Associate Medical Editor
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