Introduction: Umbilical erythema, itching, pain, and suppuration among hidradenitis suppurativa (HS) patients form a group of symptoms that is not described in the medical literature.
Methods: A review of the medical literature combined with a case series of patients experiencing umbilical symptoms in relation to HS. These were collected among 348 HS patients connected to the Department of Dermatology at Zealand University Hospital, Roskilde, Denmark, and members of the Danish HS Association's Facebook page (Patientforeningen HS Danmark), who were asked to complete a questionnaire to better describe their symptoms.
Results: Umbilical symptoms among HS patients are previously undescribed in the medical literature. Among the outpatient clinic's patients, 7.1% (24/348) experienced umbilical symptoms, and for the Facebook group the number was 10.3% (28/272). Twenty-eight patients agreed to answer the questionnaire. Three-quarters of them experienced not only itching and erythema, but also malodorous and/or bloody umbilical discharge.
Conclusions: The description of discharge symptoms experienced by many patients is similar to the description of symptoms of an umbilical pilonidal sinus (UPS). This is a condition with a morphology reminiscent to that of HS because it is defined by sinus tract formation triggered by hair penetrating the umbilical skin. UPS could be an explanation for umbilical HS symptom.