Perineal Nodular Induration: A Trauma-induced Mass in a Female Equestrian

Abstract

A 55-year-old female equestrian presented with a 3.5 cm painful left perineal mass. Histologic examination of the excised mass showed a poorly circumscribed mesenchymal proliferation involving fibroadipose and fibrous tissue. The lesion consisted of a bland spindle cell proliferation with areas of fat necrosis, hemosiderin-laden macrophages, multinucleated histiocytes, and extracellular hyalinization with degenerative features. Immunohistochemical studies showed vimentin positivity and no staining for actin, desmin, and CD34. On the basis of clinical, morphologic, and immunostaining findings, the lesion was consistent with a diagnosis of perineal nodular induration. This lesion has been described almost exclusively in avid male cyclists with repetitive perineal trauma. A similar etiology of longstanding and repetitive perineal trauma from horseback riding is postulated for this case. Perineal nodular induration should be considered in the differential diagnosis of perineal masses in women with persistent perineal trauma, such as equestrianism, as well as other similar sport activities.

Benign Tumors and Tumor-like Lesions of the Vulva

“…16 The case reported by Devers and colleagues occurred in a 55-year-old competitive equestrian. Excision of the 3.0 Â 1.5 Â 2.5 cm mass, which extended from the perineal fat close to the ischial tuberosity led to resolution of pain.…”

“…The spindle cells stain only for vimentin, with no evidence of differentiation towards a specific soft tissue. 16 This lesion should not be confused with the unilateral labial hypertrophy termed ''bicyclist's vulva,'' 17 nor to ''horse riders perineum,'' perineal fibrosis and levator hypertrophy, which does not produce a tumor-like swelling. 18 Bicycling may also be associated with perineal numbness.…”

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

“…7 Beyond cyclists, this complication has been documented in a patient who was an equestrian and another who tested lawn mowers. 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.…”

“…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.…”

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

“…6 A recent report has described a perineal nodule in a female equestrian and has documented the histologic features. 4 We report the clinicopathologic findings in 4 cases in which vulval nodules or swellings were removed from competitive female cyclists. We believe this to represent a benign reactive pseudoneoplastic lesion, which we term reactive fibroblastic and myofibroblastic proliferation of the vulva or "cyclist's nodule.…”