Case Presentation: A 55-year-old man with type 2 diabetes mellitus, metastatic renal cell carcinoma to brain and bone despite left nephrectomy and multiple cycles of chemotherapy and recent immunotherapy with nivolumab presented 3 weeks post whole brain radiation treatment (WBRT) with 4 days of right arm pain and swelling. He visited upstate New York prior to admission but denied outdoor activities, insect or tick bites. His only medication was tapering doses of dexamethasone. His vitals were normal; there was marked tenderness, swelling and erythema extending from the forearm to the distal one-third of the arm. A hyperemic patch was noted at the dorsal medial aspect of the right hand. There was a fine papular rash to anterior chest and upper abdomen. Work-up was notable for hyperglycemia (400mg/dl), thrombocytopenia (50000/ul) and neutrophilia (80%). Right upper extremity doppler for negative for deep vein thrombosis. He was admitted for treatment of cellulitis and started on intravenous clindamycin. Lyme PCR, mycobacterial cultures and blood cultures were negative. The hyperemic patch on the dorsum of his hand progressed to a necrotic ulcer. The Dermatology service performed a skin biopsy which demonstrated marked inflammatory changes. Skin culture yielded Pseudomonas aeruginosa which was consistent with the diagnosis of Ecthyma gangrenosum. He was subsequently started on a four-week course of Cefepime with significant clinical improvement.
Discussion: Ecthyma gangrenosum (EG) is a rapidly evolving skin and soft tissue infection that is most commonly associated with Pseudomonas aeruginosa. EG may present as a painless, erythematous maculopapular rash. Lesions may rapidly evolve to pustular and hemorrhagic bullae with necrotic ulceration, secondary to perivascular invasion by Pseudomonas aeruginosa along with the release of exotoxin A and protease release by the organism. Though commonly associated with Pseudomonas sepsis, it is important to note that EG may manifest in the absence of sepsis; likely from direct inoculation. A high index of suspicion should be maintained in patients with impaired cellular and humoral immunity, such as those receiving chemotherapy, chronic steroids and diabetic patients. Multiple sites of cutaneous infection and delayed initiation of empiric antibiotics have been associated with increased mortality. Physicians should consider EG as an early differential in patients with known risk factors presenting with evolving cutaneous infections as early empiric antimicrobial therapy with antipseudomonal agents is associated with improved outcomes.
Conclusions: Early consideration of EG in immunocompromised patients is critical especially if presenting with rapidly evolving necrotic cutaneous lesions. EG does not require the presence of associated Pseudomonas sepsis, though the presence of sepsis does portens a worse prognosis. Commencing early broad spectrum antimicrobial therapy with antipseudomonal agents will reduce the significant associated morbidity. Physicians should be cognizant of this clinically relevant skin infection to avoid delay in diagnosis and treatment.