CASE REPORT

 

A case of cyclist's nodule in a female patient

 

 

N Z Makhanya^I; M Velleman^II; F E Suleman^I

^IMB ChB, MMed Rad (Diag), FCRad (Diag) SA; Department of Radiology, Steve Biko Academic Hospital, Pretoria, South Africa
^IIMB ChB, MMed Rad (Diag), FC Rad (Diag); Department of Radiology, Little Company of Mary, Pretoria, South Africa

 

 

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ABSTRACT

Tere are few reported cases of cyclist's nodule in females. e condition has thus lent itself to synonyms such as third, supernumerary or accessory testicle. We report the imaging ndings of a perineal nodule in a 29-year-old female patient who is a known cyclist, and discuss the di erential diagnosis.

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A cyclist's nodule is an infrequently diagnosed yet fairly common condition of the perineum, affecting cyclists. It therefore requires a high index of suspicion in patients who are known cyclists. It is typically a tender, firm, soft-tissue nodule, seldom exceeding3 cm, located in the paramedian region of the perineum.^[1] The overlying skin is usually normal, but may show features of chafing or chronic irritation.

The condition is predominantly described in males,^[2] leading to it being termed a third, supernumerary or accessory testicle. Other synonyms include perineal hygroma and perineal induration.^[1]

 

Case report

A 29-year-old female patient, a known cyclist, was referred for imaging following a complaint of a painful, palpable mass on the right inferomedial buttock region.

Ultrasound (US) examination showed a well-circumscribed, heterogenously hypoechoic, solid nodule in the subcutaneous tissues, inferior to the ischial tuberosity, adjacent to the common hamstring origin (Fig. 1). The nodule measured 12 mm x 7 mm x 15 mm and showed no flow on Doppler.

 

 

A magnetic resonance image (MRI) ofthe pelvis was also performed and showed a poorly circumscribed nodule, isointense to muscle on all sequences, in the right perineum (Fig. 2).

A diagnosis of a cyclist's nodule was made based on the clinical history, the typical location of the lesion and the radiological findings.

The patient was managed conservatively with analgesia and advised to give up cycling. She was reluctant to give up the sport and opted to change the saddle, which, on follow-up, appears to have helped.

 

Discussion

A cyclist's nodule is believed to be as a result of repeated microtrauma from vibration and friction between the ischial tuberosities and the saddle, with constant rubbing of the superficial perineal fascia against the bony structures.^[1] This induces a combination of fat necrosis, collagen degeneration, myxoid changes and sometimes pseudocyst formation. ^[3] Although histologically few blood vessels are seen, the lesion is not well vascularised.

The nodules are usually fixed to the underlying deep soft tissues and are covered by normal skin.^[1] The absence of clinical features of infection excludes the diagnosis of an abscess, a common condition in this region. Rarely, in females, the vulva may demonstrate unilateral lymphoedema of the labia majora, which is attributed to the combination of chronic inlammation and damaged lymphatic low to the vulvoperineal and inguinal lymphatic vessels.^[3]

Symptoms include pain on pressure and when sitting on the saddle, which may even require the cyclist to give up the sport. Conservative management such as local corticosteroid injection is described; however, deinitive treatment involves removing the causative agent. The lesions have been reported to recur, even after excision.

Most articles report the histological characteristics of the lesions more than the imaging characteristics. If the diagnosis is suspected, then the imaging modality of choice is US, where the diagnosis can be made with certainty. US demonstrates a hypoechoic solid nodule, without any increased Doppler signal. Small internal cystic and/or fatty areas may also be seen, giving the nodule a slightly heterogenous appearance, as in our patient. On computed tomography and MRI, this hypovascular lesion should show no uptake of contrast agent.

The primary role of imaging is to determine the exact extent of the lesion, and in most cases, US will suffice for imaging evaluation. Imaging has an additional role in the differentiation between cyclist's nodule and other causes of perineal swelling. The differential diagnosis includes abscess, epidermal cyst, and benign and malignant tumours (fibroma, soft-tissue sarcoma or metastasis).^[3]

The MRI was performed at no cost to the patient, for academic purposes of demonstrating the MRI features of a known cyclist nodule. For this reason, no contrast was given. A fluid-sensitive sequence was performed in order to evaluate for features of acute inf ammation.

The sonographic findings were more obvious than the MRI findings where the lesion, being isointense to adjacent soft tissues on al sequences, was fairly diicult to locate.

 

Conclusion

Recreational history of cycling should be sought in all patients including females, when a non-infective sot-tissue nodule in th perineal region is seen, as the diagnosis could be a cyclist's nodule.

 

References

1. Van de Perre S, Vanhoenacker FM, Vanstraelen L, Gaens J, Michiels M. Perinea nodular swelling in a recreational cyclist: diagnosis and discussion. Skeletal Radio 2009;38:933-934. [http://dx.doi.org/10.1007/s00256-009-0731-9]        [ Links ]

2. McCluggage WG, Smith JH. Reactive fibroblastic and myofibroblastic proliferatioi of the vulva (cyclist's nodule): A hitherto poorly described vulval lesion occurrin in cyclists. Am J Surg Pathol 2011;35:110-114. [http://dx.doi.org/10.1097PAS.0b013e3181ffd8ab]        [ Links ]

3. Leibovitch I, Mor Y. The Vicious Cycling: Bicycling Related Urogenital Disorders. Eu Urol 2005;47(3):277-286. [http://dx.doi.org/10.1016/j.eururo.2004.10.024]        [ Links ]

 

 

Corresponding author: NZ Makhanya (makhanya.nz@gmail.com)