Paediatric Sweet's syndrome with pulmonary involvement triggered by severe inflammatory bowel disease and emergent total abdominal colectomy with literature review

Abstract Sweet's syndrome (SS) is a neutrophilic dermatosis characterised by the acute onset of erythematous papules or plaques and a constellation of symptoms including fever, leucocytosis, and histopathology demonstrating nodular, pustular, or diffuse infiltrate of neutrophils with marked papillary oedema. SS can be a manifestation of inflammatory bowel disease and often coincides with periods of disease flares. Only a few cases of SS associated with ulcerative colitis are reported in the literature, and no cases have involved pulmonary manifestations in the paediatric population. We present a case of a 14‐year‐old girl presenting with new onset ulcerative colitis requiring emergent colectomy with subsequent development of pulmonary SS. Treatment consisted of intravenous and oral corticosteroids and dapsone. SS should be considered in the differential diagnosis of prolonged fever with cutaneous involvement and systemic symptoms. Special consideration should be given to paediatric patients with extracutaneous manifestations, particularly pulmonary involvement.


| INTRODUCTION
In 1964, Dr. Douglas Sweet coined the term 'acute febrile neutrophilic dermatosis' to describe the abrupt onset fever, leucocytosis, painful plaques, and dense neutrophilic infiltrates on histopathology. 1 Known as Sweet's syndrome (SS), it can be seen with malignancy, infection, and inflammatory diseases.Common systemic symptoms include myalgias, arthralgias, and fever. 2 Pulmonary involvement is a rare and severe manifestation; the development of interstitial infiltrates is often preceded by the cutaneous manifestations. 3SS is rare in the paediatric population, and pulmonary manifestations in the paediatric population are even more sporadic. 4We present the striking case of a 14year-old girl with SS with pulmonary involvement in the context of new-onset ulcerative colitis requiring emergent surgical resection.

| CASE REPORT
A 14-year-old girl sought emergency treatment after 4 weeks of frequent bloody stools, severe abdominal pain, anaemia, fever, and tachycardia; she was diagnosed with ulcerative colitis.Oral corticosteroids, adalimumab, and infliximab were trialed with no response.Total parenteral nutrition and transfusion-dependent, she underwent total abdominal colectomy with end ileostomy.On postoperative day 1, she developed leucocytosis, painful pustules on her entire abdomen (Figure 1a), and haemorrhagic papules at sites of line placement and blood draws (Figure 1b).Antivirals and antibiotics were commenced while awaiting the results of the infectious workup, as postoperative infection or abscess was the primary working diagnosis.Due to daily fevers and worsening labs, dermatology was consulted, and skin biopsies were obtained.
Histopathologic evaluation showed epidermal and papillary dermal microabscesses composed of neutrophils with leukocytoclastic debris (Figure 2a).Acantholysis was seen in the suprabasal layer with

Major criteria
Minor criteria  2b).Infectious workups were negative, including serial blood cultures, viral studies, tissue cultures, and special stains on histopathology.Intravenous solumedrol was initiated at a dose of 1 mg/kg/day with rapid improvement.Diagnosis of the pustular variant of SS was made.She was discharged on a slow tapering course of prednisone.Fifteen days after discharge, during her steroid taper, our patient developed pleuritic chest pain, cough, fatigue, poor concentration, headache, and blood in her colostomy bag.Chest CT scan showed numerous bilateral pulmonary cavitary lesions with a peripheral soft tissue rim and ground glass opacities (Figure 3a,b).Pulmonary infectious workup was negative including negative tissue culture from lung biopsy and bronchial alveolar lavage.Tissue sampling of the lung showed neutrophilic abscesses and fibrinopurulent necrotic debris.She experienced a recurrence of painful pustules on her abdomen and legs which coincided with the development of pulmonary symptoms.Prednisone dosing was increased and dapsone was started.Two days later, her symptoms improved.Six months after discharge, she remains in remission on dapsone.

| DISCUSSION
SS, or acute febrile neutrophilic dermatoses, is a hypersensitivity reaction typically seen in adults; children and adolescents comprise only 5%-8% of cases, and approximately 80 cases are reported in the literature. 4,5S diagnostic criteria require 2 major and at least 2 minor criteria (Table 1). 6The pathophysiology of SS is not well understood.An inciting event often precedes SS and prior literature has divided SS into categories based on aetiology: classic idiopathic, para-inflammatory, paraneoplastic, pregnancy-associated, and drug-related. 7p to 30% of paediatric SS cases are associated with chronic inflammatory conditions. 7A rare cause of paediatric SS is inflammatory bowel disease, and cutaneous symptoms typically correspond with periods of active disease. 8Disease associations by paediatric age group and recommended workups have been published. 9S is not solely a skin disease and is well-known to have extracutaneous manifestations.Arthralgias, conjunctivitis, and myalgias are common extracutaneous manifestations.Pulmonary manifestations are an unusual and severe complication of SS.Pulmonary involvement in SS manifests as neutrophilic alveolitis with corticosteroid-responsive culture-negative pulmonary infiltrates.Only about 5% of paediatric SS have lung findings on imaging. 10Five cases of pulmonary SS have been reported, and SS with pulmonary involvement triggered by inflammatory bowel disease has not been described to date.Although a recent sole case of a paediatric patient with pyoderma gangrenosum and pulmonary findings has been reported, there have been no cases thus far of inflammatory bowel diseasetriggered SS with pulmonary findings. 11(Table 2).
Our patient met all major and minor criteria for SS in the perioperative period while in critical condition due to non-treatment responsive ulcerative colitis.Although SS should be included in the differential in all patients who meet diagnostic criteria, infectious workup should be thorough and negative, as in our patient.
Recognition of pulmonary SS is paramount.Literature has shown that cases of SS with pulmonary involvement can cause bronchiolitis obliterans organising pneumonia, a rare, potentially fatal complication if left untreated. 9In conclusion, this case highlights SS as a rare multisystem disease in children, that may present with extracutaneous manifestations including pulmonary involvement.

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I G U R E 1 (a) Disseminated pustules on an erythematous base on abdomen; (b) recent pustule marked in ink from recent venipuncture.F I G U R E 2 (a) Haematoxylin and eosin of skin biopsy showing papillary dermal microabscesses composed of neutrophils with leukocytoclastic debris; (b) haematoxylin and eosin of skin biopsy showing suprabasal acantholysis with neutrophilic inflammation.F I G U R E 3 (a, b) Axial and coronal CT Chest with contrast showing right upper lobe cavitary lesion and left upper lobe nodule both with associated surrounding ground glass changes.T A B L E 1 Diagnostic criteria for the diagnosis of Sweet's syndrome.6 Reported cases of Sweet's syndrome in the paediatric population, as well as 1 case of pyoderma gangrenosum.
1. Abrupt onset of typical cutaneous lesions 2. Histopathology consistent with Sweet syndrome 1. Preceded by one of the associated infections or vaccinations; accompanied by one of the associated malignancies or inflammatory disorders; associated with drug exposure or pregnancy 2. Presence of fever and constitutional signs and symptoms