A 40-year-old man was followed up by the dermatology department for presenting painful nodular gluteal lesions with purulent drainage. He was histologically diagnosed with deep suppurative cystic folliculitis, compatible with acne conglobata, with positive culture for Staphylococcus aureus. He was treated with prednisone (15 mg/day), isotetricin and rifampicin without improvement. In addition, he had a one-year history of 25 kg weight loss and abdominal pain, with onset of fever in recent weeks. The patient was referred for admission. On physical examination he was cachectic, with multiple nodular lesions in the gluteal and perianal region with scarring between them, draining purulent material. Laboratory tests showed severe iron deficiency anaemia (Hb: 7.2 g/dl), increased acute phase reactants (CRP:13) and signs of malnutrition (albumin: 2.49 g/dl, cholesterol: 8.3 mg/dl). A colonoscopy was performed, showing pseudopolyps, ulcers and a mucous cobblestone appearance in the rectum and transverse colon, as well as two fistulous orifices; the histological diagnosis was inflammatory bowel disease of the Crohn's disease (CD) type. A pelvic MRI showed a left perianal fistula with extension to the left thigh root. Treatment was prescribed with high-dose steroids, 5-ASA, antibiotics and azathioprine, with a notable clinical and analytical improvement and practical resolution of the skin lesions. In this case, the existence of another diagnosis (acne conglobata) together with the presentation of CD as perianal disease (EPA) led to a delay in diagnosis, which may have been a determining factor in the development of these severe lesions.

