Teaching Case

A 33-year-old male patient with no relevant medical history complaining of increasing perineal and buttock pain with swelling and pustular skin lesions over the past year.

Clinical examination revealed dermal thickening and induration with extensive erythematous and pustular lesions with purulent discharge in the gluteal, femoral and perineal regions bilaterally.

An MRI of the pelvis was performed, demonstrating symmetrical thickening of the skin and induration of the subcutaneous planes of the perineum, natal cleft, perineal region, scrotum and medial aspects of both tights. In these regions, oedema and inflammation were also present, as areas of low signal on T1-weighted images and high signal on T2-weighted and SPAIR images.

After intravenous gadolinium administration, there were multiple rim enhancement areas, compatible with abscesses, some of them communicating, consistent with sinus and fistula tracts. No communication with the pelvic organs were detected.

There were also several enlarged lymph nodes in both inguinal regions that showed homogeneous enhancement.

Hidradenitis suppurativa is a chronic inflammatory skin disease of unknown cause that manifests by recurrent abscess, sinus tracts and scarring. [1] The disease has a predilection for specific regions of the body, such as the axilla and the genito-femoral area. [1, 2]. It has an autosomal dominant inheritance pattern and significant female preponderance. [1, 3, 4]
Hidradenitis suppurativa has been associated with many disorders, such as acne conglobata, dissecting cellulitis of the scalp, and pilonidal cyst. [1] It has also been linked to several genetic disorders (a few case reports have described an association with keratitis-icthyosis-deafness syndrome and interstitial keratitis). [1]
Several case reports and studies have suggested an association between hidradenitis suppurativa and Crohn's disease, with recent evidence supporting the role of immune imbalance in both conditions. [1, 5]
Furthermore there appears to be a strong association between obesity, smoking, and hidradenitis suppurativa. [1, 5]
The diagnosis of hidradenitis suppurativa is clinical, but visual inspection is limited to the assessment of the disease severity and extension. [3] Hence, imaging allows to detect the actual type and extent of anatomic abnormalities. It may also allow adequate therapeutic planning and monitoring. MRI is the imaging technique of choice to assess the extent and possible complications of this disease. [2]
MRI findings are relatively nonspecific and include marked thickening of the skin with induration of the subcutaneous tissues that are of low signal on T1-weighted images and high signal on T2-weighted and STIR images. [2, 4, 6] Subcutaneous abscess can also be seen as areas of low signal on T1-weighted images and high signal on T2-weighted and STIR images, showing rim enhancement after IV contrast administration. Communication between these areas can be established, forming fistulas and sinus tracts. [2, 4, 6]
Bilateral inguinal lymphadenopaties are also a common finding. [2, 4, 6]
Treatment options include long-term antibiotherapy, antiandrogens, tumour necrosis factor alfa-inhibitors, and surgery. [1]
Hidradenitis suppurativa is a rare chronic, often debilitating disease that typically affects the genitofemoral area and axillae. MRI may help define the extent of anogenital disease and assess response to treatment.