Ecthyma gangrenosum (EG) is a rare skin infection [1]. It may be a systemic infection occurring on healthy skin mainly, but not exclusively, in immunocompromised patients; thus, it may be a manifestation of an underlying clinical entity [1] [2] [3]. The pathogen of ecthyma gangrenosum is Pseudomonas aeruginosa, which is a gram-negative, aerobic coccobacillary bacterium [4]. EG initially presents as a round, painless erythematous macule that later becomes nodular bullous or pustular with an indurated base and margin [1] [4] [5]. EG is clinically important not only because it is an infection with a potentially serious outcome, but may also signal the presence of a predisposing condition. The most common risk factor for EG is neutropenia in the context of malignancy or immunosuppressive therapy. EG has rarely been reported in healthy individuals [5]. Treatment is based on parenteral antibiotic therapy adapted to the antibiogram (third-generation cephalosporin, fluoroquinolones). We report the case of a 12-month-old infant who presented with EG without known predisposing factors, and who developed neutropenia during admission.

This was a 12-month-old male infant referred from a peripheral facility for management of facial swelling with fever. His ante- and perinatal history included a 15-day hospitalization for early neonatal infection. He was breastfed for six months before diversification and his vaccination status was up to date according to the Senegalese EPI. In addition, there was a delay in psychomotor development (no sitting or standing at his current age). The examination on admission showed a fair general condition, hyperthermia at 39˚C, tachycardia at 136 beats/minute, and polypnoea at 48 cycles/minute. The weight-for-height index with a z-score of 3DS was also found. The dermatological examination on entry revealed a brownish inflammatory infiltrated placard extending to the mandibular, sub-chin, and retro-auricular occipital regions and rapidly evolving towards necrosis (Figure 1), a large swelling predominantly on the upper right eyelid preventing the opening of the eyes associated with oral ulceration. The rest of the physical examination was normal. Biological abnormalities were hyperleukocytosis (27,500/mm³) with a predominance of neutrophils (19,780/mm³ or 72.0%), an elevated CRP of 198.3 mg/L, and an increase in muscle enzymes (CPK: 295 U/L, LDH: 1136 U/L). Renal function, blood ionogram, HIV-PCR, serum protein electrophoresis, CD4 and CD8 lymphocyte counts were normal. The blood culture was negative and the microbiological examination of the skin samples showed Pseudomonas aeruginosa sensitive to fosfomycin, gentamicin, and tobramycin and intermediate to imipenem, aztreonam, and ciprofloxacin. He was treated with intravenous antibiotics (amoxicillin + clavulanic acid 80 mg/kg/day), local care, and nutritional management. He then underwent necrosectomy under general anaesthesia (Figure 2) and antibiotic therapy was secondarily adapted to the antibiogram (imipenem + gentamicin).

The evolution was favourable with good healing of the lesions and stable apyrexia. The patient was discharged from hospital on day 26, with per on antibiotics and care every two days.

Pseudomonas aeruginosa is one of the bacteria frequently implicated in opportunistic infections and responsible for many hospital-acquired infections. The infection is represented in its most severe form by ecthyma gangrenosum [6]. Ecthyma gangrenosum (EG) is a severe skin infection caused by Pseudomonas aeruginosa, most often occurring in an immunocompromised environment [6]. In children, it occurs in the context of primary immunodeficiency, cancer (50%) and in particular acute leukaemia, acquired neutropenia and haemophagocytic syndrome [7]. In our patient, severe malnutrition was present. Its occurrence in immunocompetent patients is rare, although some case reports describe occurrences in healthy children [8]. A review of the literature showed that most of these patients, although previously healthy, had risk factors for the development of ecthyma gangrenosum or had unrecognised underlying medical conditions. Our age was 12 months, whereas Zommorodi A et al. [8] found that of the 18 children, 16 were infants under 22 months of age. The patient reported in this study had lesions located on the face. This finding was also found in the study by César AML et al. [9] who also reported a facial location in 3 cases out of their series of 8 patients. Other locations described were anogenital and axillary. EG typically begins with erythematous macules followed by the formation of bluish haemorrhagic bullae that rupture and give rise to necrotic ulcerations surrounded by an erythematous halo. The patient described here had an unusual clinical presentation with the appearance of a rapidly necrotic lesion progressively extending to the entire sub-mandibular area, reflecting the great clinical polymorphism of this condition. The most common risk factor for EG is neutropenia in immunocompromised patients. Neutrophils are the main host defence against Pseudomonas infection and their qualitative and quantitative deficiency are important risk factors for the development of ecthyma. Neutrophil values below 500/mm³ present the greatest risk of severe infection [10]. We found the patient to have neutropenia of 1000/mm³ during hospitalisation. A review of the English literature showed that many apparently healthy patients with ecthyma gangrenosum were neutropenic at the time of presentation [8]. Although neutropenia is a risk factor for the development of ecthyma gangrenosum, it has been suggested that Pseudomonas infection can cause a transient neutropenic state by producing a toxin that inhibits neutrophil migration into infected areas and decreases the number of circulating neutrophils [8]. Of the five children described by Neta C et al. [10], four were neutropenic with an absolute neutrophil count < 1500 mm³ after presenting with ecthyma gangrenosum. This indicates that although the absolute neutrophil count at presentation may be near normal, it may collapse soon after to severe neutropenia and sometimes remain severe and even require treatment. This may be partly explained by the fact that the Pseudomonas infection itself reduces the number of circulating neutrophils [10]. Another possible explanation is that these patients were neutropenic before presentation and had a proliferative response to the acute infection resulting in a temporarily normal absolute neutrophil count. Our patient was undernourished with a z-score of 3DS. César A M L et al. [9] in their series of 8 cases found undernutrition as a risk factor.

This observation is rare because of its location, its early occurrence, and its non-neutropenic background.

The authors declare no conflicts of interest regarding the publication of this paper.

Diouf, J.B.N., Barry, H.M., Sarr, L.P. and Ba, N.D. (2022) Ecthyma Gangrenosum about a Case at the Centre Hospitalier Roi Baudoin de Guédiawaye in Senegal. Open Journal of Pediatrics, 12, 652-656. https://doi.org/10.4236/ojped.2022.124066