Reactive Fibroblastic and Myofibroblastic Proliferation of the Vulva (Cyclist's Nodule)

Abstract

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."

Perineal nodular induration: a report of three cases in France

“…2,3 Perineal nodules are not exclusive to men; female cases have also been reported. 1,4 The appearance of the nodules is stereotypical. The lesion can be unilateral or bilateral, be situated beneath the scrotum or on the labia majora, and measure between 2 and 5 cm.…”

“…Among these, perineal nodular induration is a little known complication, referred to using a variety of terms including perineal nodular induration of the cyclist, ischiatic hygroma, accessory testicle, third testicle, or biker's nodule. In the following study, we report on three cases of perineal nodular induration in cyclotourists.…”

Surgical excision of perineal nodular induration: A cyclist’s third testicle

“…8,9 It is more commonly seen in males, but recently, five female cases have been reported. 9,10 Its latency period varies from a few weeks to one year. Although the nodule in our case was mobile, most reports state that it is fixed to the soft tissue or ischial tuberosity, has a fibrous to elastic consistency, and is covered by normal skin.…”

Lymphatic drainage abnormalities in a child presenting as an unilateral vulvar swelling: a case of ‘Bicyclist's vulva’

“…2,3,7 Similarly, it has been reported that these repeated microtrauma could also result in conjunctive tissue damages known as 'perineal nodular induration' or 'cyclist nodule'. 7,8 However, the histological aspect is characterized by a vulvar fibroblastic and myofibroblastic proliferation, 8 whereas bicyclist's vulva seems to have a normal skin biopsy.…”