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17 September 2014 - Case of the Week #326

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Thanks to Dr. Ankur Sangoi, El Camino Hospital, California (USA), for contributing this case. This case was reviewed in May 2020 by Dr. Jennifer Bennett, University of Chicago and Dr. Carlos Parra-Herran, University of Toronto. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.


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Case of the Week #326

Clinical History:
A 34 year old woman had "perineal cysts" that were biopsied. She was an avid cyclist.

Micro images:

H&E images

What is your diagnosis?

Perineal nodular induration

Perineal nodules are rare reactive lesions reported in male and female cyclists and equestrians, due to repetitive perineal trauma (Hautarzt 2000;51:763, Int J Gynecol Pathol 2010;29:398). They have also been termed cyclist's nodule, reactive fibroblastic and myofibroblastic proliferation of the vulva, and "third testicle of the cyclist" (Histopathology 2003;42:615). In women, a recent report describes 4 cases of unilateral nodules or swellings of the labium major in competitive cyclists ages 15-45 years (Am J Surg Pathol 2011;35:110). Histologically, there was a mixture of adipose tissue, hyalinized tissue with bland spindled fibroblasts, blood vessels and nerve fibers, with variable perivascular lymphocytic infiltrate, thick cords of fibrous tissue, elastic fibers and epithelioid, plasmacytoid or ganglion-like cells.

The spindle cells cells were immunoreactive for estrogen receptor and plump mesenchymal cells were positive for smooth muscle actin, consistent with myofibroblasts. These cells were negative for desmin, S100, CD34 (but see Int J Surg Pathol 2014;22:71) and HMGA2.

The differential diagnosis includes various other mesenchymal lesions, which have a different clinical setting.

These lesions are benign, but may recur. In this case, after cessation of cycling and rest, the nodule went away.

Nat Pernick, M.D., President
and Shivani Thakore, Associate Medical Editor
PathologyOutlines.com, Inc.
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Email: NatPernick@PathologyOutlines.com
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