Ecthyma gangrenosum in a 7‐year‐old girl: Is it a sign of acute lymphoblastic leukaemia?

Dear Editors,

We present a remarkable case of ecthyma gangrenosum (EG) occurring in a young and apparently healthy child, in which the suspicion of this rare condition led to a specific diagnosis and to the recognition of an underlying systemic condition.

A 7‐year‐old female Caucasian patient presented to the emergency department of our hospital complaining the recent onset of abdominal skin lesions associated with burning pain. The parents reported sudden appearance of patches following a bath in the sea. Skin examination showed macules with central necrosis surrounded by an erythematous halo. Hyperpyrexia with 39°C body temperature and sensory obnubilation were assessed. Routine blood tests showed: anaemia (HGB 9.9 g/dL), leukopaenia (WBC 1.9 10³/μL) with neutropaenia (neutrophils 15.2%), hyponatraemia (Na 131 mmol/L), d‐dimer 257 μg/L, LDH 323 U/L. Chest‐XR reported diffuse interstitial thickening and abdominal US reported increased dimension of the spleen, with diffuse homogeneous globous ecostructure. A tissue swab was also obtained from a cutaneous lesion and culture diagnosed a Pseudomonas aeruginosa (PSAE) infection. Clinical presentation and identification of the pathogen allowed us to diagnose EG caused by PSAE. Systemic antibiotic therapy was then initiated with amoxicillin‐clavulanate and piperacillin‐tazobactam. Clinical improvement was evident over the course of therapy with progressive resolution of the febrile state and of the cutaneous lesions. The patient was transferred to the paediatric onco‐haematology ward for further diagnostic investigations. A bone marrow biopsy showed 90% blasts and led to a diagnosis of acute lymphoblastic leukaemia (ALL) of B‐cell lineage. This acute form of leukaemia is associated with excellent prognosis in patients undergoing steroid and chemotherapy regimens (Figure 1).

Figure 1.

Ecthyma gangrenosum. Two lesions showing central necrosis surrounded by an erythematous halo on the abdomen

EG is a rare disorder of the skin due, in the majority of cases, to a PSAE infection. Typical presentation includes maculo‐papular lesions that rapidly evolve to show central necrosis surrounded by an erythematous halo. Preferred sites are the axilla and groin, followed by the trunk and the face. In this report, skin involvement was predominant at the trunk.1, 2, 3 Bacteraemic and non‐bacteraemic forms have been described.1 In the first case, haematogenous dissemination of the pathogen is responsible for multisystem failure: apart from the skin manifestations, patients present pulmonary and renal impairment, and, in severe cases, sensory compromise. In the second case, trauma directed to the skin is responsible for entry of pathogens and onset of skin lesions. PSAE is a round‐shaped Gram‐negative bacterium. It is a ubiquitarian agent with predilection for moist environments, such as soil and especially water, including improperly sanitised swimming pools.2 In this case, history was indicative of recent contact with sea water. PSAE is notoriously implicated in infection concerning immunocompromised patients. Categories at risk include patients with innate or acquired immunodeficiency,4 elderly individuals, and hospitalised subjects, as health care facilities are a common source of infection from multi‐drug resistant organisms.2 Our patient presented with neutropaenia, which is an established risk factor for this kind of infection.2, 3, 5 Investigation of neutropaenia is a challenge as it may be a primitive condition predisposing to infection or be secondary to infection, as the pathogen may induce transitory neutropaenia through toxins capable of inhibiting granulocyte migration.2, 6 Neutropaenia, which is a common feature of immunocompromised patients and is rare in apparently healthy individuals, may show an underlying pathologic condition and demands further investigation to exclude possible causes. In a recent report, hospitalisation of an infant for PSAE sepsis led to molecular and genetic diagnosis of X‐linked agammaglobulinaemia.7 Diagnosis of EG requires suggestive clinical presentation and positive culture confirming infection on skin swab or, in the case of bacteraemia, on blood culture samples. Histologic features are a rich leukocyte infiltrate predominantly composed of neutrophils. The clinical evidence of necrosis is because of bacterial replication and infiltration in blood vessel walls and perivascular space causing ischaemic necrosis.2, 4, 5 PSAE is the most common pathogen responsible for EG, but evidence of coinfection8 and of infection from different agents, including Staphylococcus aureus, Escherichia coli, Klebsiella spp., has been reported in the literature.2, 3 Paediatric patients are often involved: EG has been described in immunocompromised subjects following heart transplant9 or suffering from ipogammaglobulinaemia2 or malignancies,3 such as in our case. In other cases, no predisposing condition was apparent.6 Prognosis is variable depending on overall clinical conditions and extent of involvement, potentially becoming severe in case of bacteraemia. We witnessed a rapid clinical improvement following antibiotic therapy with piperacillin‐tazobactam and amoxicillin‐clavulanate. Considering the development of different drug resistance mechanisms by this pathogen,5 association of penicillin and beta lactamase inhibitor is the treatment of choice in PSAE infection.5, 6 Combination therapy is preferred to monotherapy because it carries increased efficacy and reduced risk of fatality.2

In conclusion, EG is a rare cutaneous disorder because of PSAE infection that may be indicative of a septic state and, consequently, be potentially fatal. Rapid identification of this condition, guided by the typical skin manifestations, is crucial for early therapy and for the recognition of underlying disorders.