Locoregional multiple nodular panniculitis induced by Pseudomonas aeruginosa without septicemia: three cases and focus on predisposing factors.

IMPORTANCE: Pseudomonas aeruginosa-induced locoregional multiple nodular panniculitis without septicemia is an underreported condition, with only 3 cases reported to date. We report 3 new cases of P aeruginosa-induced multiple nodular panniculitis without septicemia and describe common features among all 6 cases, thus providing the first description, to our knowledge, of the natural history and potential predisposing factors for this entity.

OBSERVATIONS: Median age of the 6 patients was 74 years (range, 54-84 years). Patients had inflammatory nodules on a lower limb (n = 6) that were unilateral (n = 6) and had no fever (n = 5). Blood cultures were negative (n = 5). Skin biopsy specimens revealed panniculitis (n = 5), with skin cultures positive for P aeruginosa (n = 6). Skin nodules resolved with systemic antibiotics (n = 5). The comorbidities recorded were type 1 or 2 diabetes mellitus (n = 5), overweight (n = 3), and combined locoregional anatomical changes in the lower limbs (n = 5). Local skin injury, which constituted the portal entry, was present in all cases, especially leg ulcers (n = 3).

CONCLUSIONS AND RELEVANCE: We describe P aeruginosa-induced locoregional nodular panniculitis as a distinct entity. This should be investigated in elderly, diabetic, overweight patients with inflammatory nodules on a lower limb associated with locoregional anatomical changes and skin injury, with the optimal antibiotic regimen introduced as rapidly as possible.