Introduction Within Inflammatory Bowel Disease (IBD), perineal lesions are a common extra-intestinal manifestation, yet may mask other entities. Including several etiologies across a number of subspecialties, most of which are better appreciated in adulthood. This report focuses on an unusual dermatological association with IBD, presenting at an atypical time in the disease course.

Case Report 11-year-old obese Hispanic female presented with the chief complaint of epistaxis and was noted to have painful lower extremity nodules consistent with erythema nodosum and gluteal cleft lesions. Review of systems revealed fatigue, anorexia and diarrhea for two months prior accompanied by a 6.8 kg weight loss over that period. On admission, she was febrile (38.3°C), tachycardic and hypotensive with baseline laboratory values notable for leukocytosis (13.1/nL), hypochromic microcytic anemia (hemoglobin 10.3 g/dL and mean corpuscular volume 70.3 fL), thrombocytopenia (55/nL) and evidence of systemic inflammation with elevated CRP/ESR.

Stool studies were significant for fecal leukocytes and a CT revealed mural thickening with fat stranding; segmental colitis was confirmed on colonoscopy. At that time, a punch biopsy of the gluteal lesion revealed granulomatous dermatitis, presumed to be cutaneous Crohn’s Disease (CD). Treatment was initiated with Metronidazole and Methylprednisolone. Soon after the clinical course became complicated by the development of a rectovaginal fistula. Induction and maintenance treatment were achieved with Infliximab and the patient was discharged with the diagnosis of CD with perineal involvement.

Multidisciplinary team monitoring over the following three years ensued before the patient reported progression of intertriginous lesions, this time to the axillae and infra-mammary areas. Punch biopsy at the new lesion established the diagnosis of Hidradenitis Suppurativa (HS), with a pathological confirmation.

Discussion HS is a chronic inflammatory dermatological disease of the apocrine glands, characterized by recurrent and painful, deep-seated nodules, abscesses, sinus tracts and/or fistulas. It affects inverse areas of the skin following the distribution of apocrine glands. Prevalence is higher post-puberty, with smoking and obesity acting as risk factors. The association with IBD, particularly CD is stronger in the severe phenotype and in pancolitis. The formal diagnosis is made on average one decade after the onset of IBD. Up to 25% of IBD patients experience extra-intestinal manifestations, perineal pathology accounts for 50% of the cases. Yet, in the absence of extra-perineal intertriginous involvement, the possibility of HS may be less recognizable. Improved awareness to this association among Paediatricians and Paediatric Gastroenterologists is important as co-pathology may require treatment escalation to immunosuppressive agents or alterations to monoclonal antibody regimen. More intensive treatment is often required as disease remission is harder to achieve for HS than CD.

Conclusion HS, when associated with CD, typically occurs one decade after the initial IBD diagnosis. This case presents a much shorter interval between such diagnoses, and potentially a dual presentation. This has not been appreciated in the literature to date and possibly suggests rare but earlier association when present. Analysis of a larger pediatric IBD cohort with HS will help clarify the pattern of association.