Reactive Fibroblastic and Myofibroblastic Proliferation of the Vulva (Cyclist's Nodule): A Hitherto Poorly Described Vulval Lesion Occurring in Cyclists

Department of Pathology, Belfast Health and Social Care Trust, Northern Ireland.
The American journal of surgical pathology (Impact Factor: 5.15). 01/2011; 35(1):110-4. DOI: 10.1097/PAS.0b013e3181ffd8ab
Source: PubMed


Perineal nodules occurring in male cyclists are reported in the literature, although the histologic features are not extensively documented. There has been little description of similar lesions in the female population. We describe 4 cases in which a vulval nodule or swelling developed in competitive female cyclists aged 15 to 45 years. The lesions were unilateral and occurred on the right or left labium majus (2 cases each). The histologic features were similar in all cases and consisted of a haphazard admixture of adipose tissue, variably cellular hyalinized tissue containing bland spindle-shaped fibroblasts, blood vessels, and nerve fibers. In some areas, thick cords of fibrous tissue imparted a keloid-like appearance. Other histologic features included plump mesenchymal cells with round or ovoid nuclei and abundant eosinophilic cytoplasm resulting in an epithelioid, plasmacytoid, or ganglion-like appearance (2 cases), a lymphocytic infiltrate around blood vessels (3 cases), foci of fat necrosis (1 case), and collections of elastic fibers (2 cases). One case recurred, the histologic features of the recurrent lesion being identical to the original. The overall morphologic appearances, especially in the cases with plump mesenchymal cells, bore some resemblance to proliferative fasciitis. Immunohistochemically, the cells were estrogen receptor positive and the plump mesenchymal cells were smooth muscle actin positive, in keeping with myofibroblasts. Desmin, S100, CD34, and HMGA2 were negative. Pathologists should be aware of this pseudoneoplastic lesion occurring on the vulva, which arises in a specific clinical setting and has the potential to be misdiagnosed as a variety of other mesenchymal lesions. We term this lesion as reactive fibroblastic and myofibroblastic proliferation of the vulva or "cyclist's nodule."

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    ABSTRACT: Perineal nodular induration (PNI) is a fibroblastic pseudotumor that presents almost exclusively in male cyclists. It develops in the soft tissues of the perineum immediately posterior to the scrotum, as a bilateral or single, central or lateralized mass. Although well known to sport medicine specialists, it is a scarcely documented entity in the pathology literature. We present 2 cases of PNI with fine-needle aspiration cytology and immunohistochemistry. They consisted of a paucicellular fibroblastic proliferation containing CD34-reactive spindle and epithelioid cells, small foci of fibrinoid degeneration, numerous blood vessels, and entrapped groups of mature fat cells. Our cases show that the histopathological features of PNI are more varied than those previously described and its immunohistochemical profile is wider. A central cystic focus and a zonal pattern are not consistent features of this entity. The lesional cells can express CD34, a hitherto unreported immunohistochemical finding.
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