28 May 2020

Case study: cyclist with bilateral pain in buttocks

Clinical

An interesting case study in rheumatology…

HISTORY

A fit man of 60 years presented with severe bilateral discomfort in the region of his ischial tuberosities while cycling at least three times a week for an average weekly distance of 180km.

He had purchased a new bicycle saddle six months prior to presenting. He rapidly developed bilateral pain in his buttocks during cycling but was not symptomatic otherwise and constitutionally well. He was an office worker and was not troubled sitting at work or in the car or train. 

He was advised that he “would adapt” to his new saddle but he gradually got worse.  After two months he tried a series of different saddles but his condition did not improve. 

On examination, the only positive sign was tenderness to light pressure on the infero medical aspects of both ischial tuberosities with small extension along the pubic rami anteriorly. He ceased cycling, then returned after some weeks to shorter distances (approximately 30km) and slowly improved.

IMAGE FINDINGS

On MRI, axial and coronal PD and T2 fat saturated sequences demonstrate bilateral symmetric rounded 3cm nodular foci of indurated soft tissue in the perineum immediately inferior to the ischiorectal fossae. These abut the inferior aspects of the pubic rami and are associated with T2 high signal oedema extending into the adjacent adductor magnus musculature.

DIAGNOSIS

Although not commonly reported, these lesions are typical of cyclist ischial hygromas/perineal nodular induration, a relatively rare and often misdiagnosed condition secondary to chronic repetitive microtrauma, most commonly affective competitive cyclists, particularly mountain bikers. These lesions are also referred to in the literature amusingly as “third testicles”. This is due to increased friction resulting in fibroblastic keloid type reactive tissue.

Dr Sebastian Fung is a musculoskeletal radiologist who undertook an MRI imaging fellowship in Hospital for Special Surgery in New York. He now works in Sydney at St Vincent’s Private Hospital and Mater Hospital