First Episode of Axillary Acne Inversa in a Teenager on Infliximab Therapy for Crohn Disease

Acne inversa (AI), also known as hidradenitis suppurativa, is a chronic skin disorder characterized by the development of abscesses, fistulas, and scarring with a relapsing pattern. The defect is believed to be in the pilosebaceous follicular epithelial cells, and apocrine gland involvement is secondary in nature (1). AI can be familial, and inheritance is consistent with an autosomal dominant pattern. The lesions are predominately located in skin folds that have terminal hairs and apocrine glands such as axilla, groin, perineal region, inframammary tissue, and scalp. A higher incidence is observed in African Americans, and the majority of the patients experience the first symptoms after puberty. It has been occasionally associated with psoriasis, pyoderma gangrenosum, seronegative arthropathies, and Crohn disease (CD), in particular (2). Historically, the treatment of AI lesions has been antibiotics, surgical drainage, and resection; recently successful results have been reported with tumor necrosis factor-α blockers including infliximab in patients with or without CD (3). Here, we report a teenager with CD and familial AI, whose first AI lesions occurred in the bilateral axillae while he was receiving infliximab therapy. A 16-year-old postpubertal African American male patient with CD presented with bilateral painful axillary lumps that had developed over a few weeks. He was diagnosed with CD 2 years ago and has been on mesalamine, methotrexate, omeprazole, iron sulphate, and infliximab who recently transferred his care to our institution. Per patient's records, he was placed on infliximab every 4 weeks’ dosing because of persistent iron deficiency anemia 22 months before transferring his care to our institution. He has had 3 endoscopies in the previous institution, and his CD has been controlled well with the present treatment. At the time of his first visit at our institution, his disease activity was categorized as inactive, and his Pediatric Crohn Disease Activity Index score was 2.5. There was no history of fever, night sweats, weight loss, cough, diarrhea, sick contacts, or interaction with kittens. He had painful lumps >2 cm, 1 in the left and 2 in the right axilla without liver or spleen enlargement or additional palpable lumps in the other parts of his body on the physical examination. The patient was evaluated by hematology/oncology for the possibility of lymphoma. Complete blood count, erythrocyte sedimentation rate, and serum lactate dehydrogenase were within normal limits. Titers for Epstein-Barr virus, cytomegalovirus, human parvovirus B19, and Bartonella were negative, and chest x-ray did not reveal any intrathoracic lymphadenopathy. He was started on oral cephalexin, and within 4 days, the lumps had gotten much smaller and were not tender anymore and appeared superficial, fixed/nonmobile, and solid palpable masses consistent with hidradenitis. Furthermore, his mother and maternal grandmother have history of recurrent axillary hidradenitis that required multiple surgical interventions. His family history was also significant for colitis in a maternal and a paternal uncle. He was diagnosed with familial AI and lesions have completely resolved later. Because he remained in remission, infliximab dosing was increased to 6 weeks’ intervals. Four months later, the patient continued to do well and Pediatric Crohn's Disease Activity Index scores at 2 subsequent follow-up visits were 2.5 and zero, respectively. DISCUSSION There have been a limited number of reported cases of AI in association with CD (2–5). Development of AI may precede or follow the diagnosis of CD suggesting a temporal relation (5). Mutations in the enzyme γ-secretase subunits leading to reduced activity have recently been described in familial cases of AI (6); however, the role of γ-secretase has not been studied in CD so far. Whether there is a cause–effect relation between these disorders is not known. It is plausible that AI and CD may result from different genetic alterations that may cosegregate. Alternatively, there may be a common basic genetic background variation, which in turn increases the development of either disorder in the presence of a more condition-specific genetic abnormality. Presence of history of AI and colitis in different family members of the case reported here suggests the possibility of the latter explanation. Infliximab is a successful drug in the treatment of CD; however, loss of efficacy has been reported in up to 35% to 40% of the patients in the long term. Less than 100 cases of AI treated with infliximab have been reported to date (7,8). A small proportion of them also had CD; successful response to infliximab has been reported in those cases. Loss of efficacy of infliximab therapy has also been reported in one third of the patients with AI (7). Of importance is the development of AI lesions while the presented patient was on infliximab therapy for CD with good control of CD activity. This observation points to the lack of preventative effect of infliximab in AI development in CD; however, it could be speculated that quick improvement in hidradenitis lesions with antibiotic treatment in our case may have been helped by the use of infliximab as well. Development of lymphomas in patients receiving tumor necrosis factor-α blockers is a rare possibility. In patients with CD, whether treated on infliximab or not, AI should be included in the differential diagnosis of lumps that occur at sites, where lymph nodes commonly reside, particularly axillary and inguinal regions. Long-term follow-up of this case may provide useful information in understanding the relation between CD and AI.