Multi-System Inflammatory Syndrome in Children (MIS-C) with Retropharyngeal Involvement Mimicking Abscess: the Therapeutic Role of Anakinra

Angela Troisi¹, Francesco Accomando^1,2, Lorenzo Mambelli¹, Federico Marchetti^1*

¹Department of Pediatrics, Santa Maria delle Croci Hospital, 48121 Ravenna, Italy

²Specialty School of Pediatrics, Alma Mater Studiorum, Università di Bologna, 40126 Bologna, Italy

*Corresponding Author: Federico Marchetti, Department of Pediatrics, Santa Maria delle Croci Hospital, 48121 Ravenna, Italy.

Received: 24 November 2022; Accepted: 12 January 2022; Published: 10 February 2023

1.Case Report

A seven-years-old girl was admitted to our pediatric unit because of persistent fever for nine days, she was not responsive to broad-spectrum oral antibiotic therapy, associated with headache, sore throat and neck pain. Physical examination showed a pharyngitis with a medial shift of the left tonsil, left lateral cervical lymphadenopathy and painful neck stiffness. There were no signs of meningeal irritation, conjunctival injection or rash, cardiothoracic objectivity was normal. Initial blood tests revealed an elevated C-reactive protein (CRP) level (47,6 mg/L), white blood cell count in range (5640/uL) with a mild lymphopenia (1190/uL), normal hemoglobin and platelets count, liver and kidney function tests in range, normal coagulation tests and troponin levels. Intra-abdominal and thoracic infectious foci were excluded (normal abdominal ultrasound and chest X-ray). Intravenous antibiotic therapy with Ceftriaxone and Clindamycin was started. A Magnetic Resonance Imaging (MRI) was performed showing inflammation of the parapharyngeal and retropharyngeal tissues, with uncertain presence of an abscess (Figure 1).

Figure 1: MRI imaging of interested parapharyngeal and retropharyngeal tissues.

After two days of parenteral antibiotic therapy the patient was still feverish and the clinical condition further deteriorated, with inappetence, oliguria, worsening of neck pain with significant stiffness, plus occurrence of bilateral non-secretive conjunctival injection, mild cheilitis, and abdominal pain. The presence of persistent fever unresponsive to antibiotic therapy, mucocutaneous inflammation, lymphadenopathy, high level of CRP, associated with previous Covid-19 infection detected, led to the diagnosis of Multi-System Inflammatory Syndrome in Children (MIS-C). Therefore, the patient was treated with intravenous immunoglobulin (IVIG) in combination with methylprednisolone 2 mg/kg and low dose acetylsalicylic acid. In spite of an initial improvement, three days after administration of IVIG with ongoing steroid therapy, there was a recurrence of conjunctivitis, painful neck stiffness, headache and fever, therefore a therapy with anakinra (4 mg/kg/day intravenous) was started, in combination with a second dose of IVIG, carrying on methylprednisolone. This therapy resulted in a swift clinical improvement, fever regression and CRP negativization. No heart involvement was observed on follow-up.

2. Discussion

Retropharyngeal edema is a rare presentation of Kawasaki Disease (KD) [1]. At MRI image, an edema and an abscess have features in common and this can lead to a clinical misjudgment. Nevertheless, an abscess usually is characterized by central liquefaction [2,3]. In literature, a few MIS-C cases present symptoms like neck pain, trismus, voice change, drooling, dysphagia, odynophagia or rarely stridor and respiratory distress with radiological findings similar to retropharyngeal abscess [4]. Both in KD and MIS-C, an important involvement of cervical lymphatic tissue can be observed, de facto KD is also called "mucocutaneous lymph node syndrome". In addition to superficial cervical lymph nodes deep lymphatic tissues can also be affected, mimicking a retropharyngeal/peritonsillar abscess [5,6]. In these cases, the international consensus guidelines on MIS-C recommend a multistep anti-inflammatory treatment [7]. First-line therapy is IVIG (dose of 2 mg/kg) plus low-to-moderate–dose glucocorticoids (1–2 mg/kg/day). In patients who do not achieve clinical improvement within 24-48 hours, an intensified therapy is recommended with either high-dose (10–30 mg/kg/day) glucocorticoids, anakinra (recombinant human IL-1 receptor antagonist, dose of >4 mg/kg/day and often 5–10 mg/kg/day), or infliximab (10 mg/kg IV x 1 dose) [7]. In more severe patients with organ dysfunction anakinra can be considered as first line therapy [7]. In the reported case, the use of anakinra in combination with a second dose of IVIG led to immediate clinical improvement, until complete healing.

Funding

Not applicable.

Acknowledgments

Not applicable.

Disclosures and Conflict of Interest

The authors have no conflicts of interest relevant to this article.

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