Cyclist's nodule: no smooth ride

Abstract

A fit and active amateur cyclist was referred by his general practitioner to a surgical oncology outpatient clinic with a slowly-growing perineal mass. Following clinical examination, the patient underwent imaging and biopsy at a tertiary soft tissue tumour centre, which diagnosed perineal nodular induration: a rare, benign tumour caused by repetitive trauma associated with 'saddle sports' such as cycling or horse riding. It is important to consider soft tissue tumours in patients who present with 'lumps and bumps'; they can occur anywhere in the body including the groin or perineum, where it is sometimes referred to as a 'third' or 'accessory' testicle in men. Although unusual, the case emphasises the importance of rapid specialist referral from primary care, and consideration of a patient's occupation and hobbies when formulating diagnoses.

“Bumpy” ride for the female cyclist: A rare case of perineal nodular induration, the ischial hygroma

“…Among cyclists, it has been referred to as an accessory testicle [ 3 , 9 ], and is dubbed the “cyclist’s nodule” or “the cyclist’s third testicle” [ 9 ] due to its characteristic singular nodularity. As such, PIN is predominantly reported in males [ 6 ]. However, PNI can occur in females [ 5 ] and is likely underdiagnosed [ 6 , 7 ].…”

“…As such, PIN is predominantly reported in males [ 6 ]. However, PNI can occur in females [ 5 ] and is likely underdiagnosed [ 6 , 7 ]. Other sports with saddle emphasis, such as equestrian sports, mountain biking, and even seated lawnmowing are also considered risk factors for PNI development [ 12 , 13 ].…”

“…Furthermore, there is potential for misdiagnosis in females [ 5 ] as the vulvar region can develop a wide range of mesenchymal lesions [ 5 , 11 ]. PNI has been mistaken for lipoma [ 6 , 8 ], and has even been referred to a specialty sarcoma center for concern of a growing paratesticular mass [ 6 ] which led to serial MRIs and biopsy. With better awareness, PNI can be diagnosed with a thorough history and physical exam [ 3 , 14 ], avoiding a more expensive workup.…”

“…Beyond ultrasound, MRI may be helpful as it provides information regarding lesion extend, as well as PNI features of fibrosis and hypovascularity [ 16 ]. MRI shows irregular hypointense T1 and hyperintense T2 signal in the perineum, just under the ischial tuberosity [ 6 ]. With PNI, there no invasion of surrounding muscle tissue [ 14 ].…”

“…Cycling is a growing sport in North America, with approximately 70,000 USA Cycling members in 2013 [ 1 ] and over 89,000 USA Triathlon members in 2016 [ 2 ]. Perineal nodular induration (PNI) is a benign pseudotumor associated with saddle sports [ [3] , [4] , [5] , [6] ], comprised of mixed fibroblastic and myofibroblastic proliferations [ 6 , 7 ]. There is a paucity of sports medicine research on PNI, and it is primarily reported in uropathological literature [ 5 , 8 ] in association with male cycling [ 7 , 8 ].…”