An 8-month-old infant was referred by a paediatrician to a dermatology outpatient clinic due to disseminated blisters and erosions failing to respond to treatment. The skin lesions were presented for about 5 weeks. According to the mother, the parents and elder brother of the boy had suffered from gastroenterocolitis at that time. All the family members presented fever of 38-38.5 C accompanied by diarrhoea and abdominal pain. On the third day of gastroenterocolitis, our patient started to present non-itchy erythematous plaques on the palms and soles, with solitary vesicles, accompanied by loss of appetite. The patient was consulted by a paediatrician, who suspected the Boston disease with secondary bacterial infection and administered an analgetic (acetaminophen), an antibiotic (amoxycillin with clavulanic acid), topical glucocorticosteroids (fluticasone and hydrocortisone), and dimetindene (oral solution). After 7 days of application, there was no response to that treatment regime. The boy was referred to a hospital, where he was consulted by another paediatrician, who administered clarithromycin. The treatment with clarithromycin was discontinued after few days, as according to the mother, erythematous circular plaques started to spread from palms and soles proximally, affecting forearms, arms, shins, thighs, and the trunk (Figure 1A). Moreover, tense blisters and vesicles on the erythematous background, initially located on distal parts of upper and lower limbs (Figure 1B), were gradually spreading to the periumbilical area (Figure 1C), the whole trunk, and the face. The skin of the scalp and diaper area was spared.
There was no family history of atopic diseases. The boy was breastfed since birth and mother did not have to use any kind of elimination diet, and the diet was expanded according to the guidelines without any disturbing symptoms. A family history of autoimmune blistering skin diseases and chronic diseases was negative. There was no recent history of vaccination prior to the onset of lesions. The boy was vaccinated only on the first day of life (against hepatitis B and tuberculosis), while other mandatory vaccinations were postponed due to mild but frequent oropharyngeal infections, transmitted mostly by older brother of the patient.
Although our patient presented new blisters every day, with some of them turning into oozing erosions covered with yellowish crusts, the boy was in a good general condition, without any additional systemic symptoms, such as fever, weakness, or pruritus. A chest X-ray ordered by a paediatrician showed slight inflammatory lesions pericardially and in the upper lung fields. Abdomen ultrasound did not reveal any abnormalities.
Interestingly, mother of the boy decided to check if the family members had COVID-19 infection, and about 4 weeks after the onset of gastrointestinal symptoms, the pertinent blood tests were performed. It turned out that our patient, older brother, and father all had IgG antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (determined by CMIA:chemiluminescent microparticle immunoassay--235 BAU/ml), while mother of the boy had a positive SARS-CoV-2 reverse transcription PCR (RT-PCR) test.
Our patient was referred to a dermatologist who suspected erythema multiforme or Kaposi varicelliform eruption with secondary infection and prescribed topical treatment with fucidic acid combined with hydrocortisone, cleansing with sodium hypochlorite, and systemic treatment with acyclovir.
As there was no improvement after 2 days of this treatment and the boy started to refuse to eat or drink, the dermatologist decided to refer the infant to a hospital. Laboratory findings showed slightly increased levels of platelets (480 x 109 per L), slight microcytic anaemia, higher levels of eosinophils (7%) in a complete blood count with differential leukocyte count, slightly elevated C-reactive protein (12 mg/dl) with negative procalcitonin (0.04 ng/ml), slightly higher D-dimer (11.64 mg/L), and slightly lower level of serum IgA (24 mg/dl). Culture from blister fluid showed growth of Streptococcus pyogenes. The RT-PCR test for the SARS-CoV-2 was negative.
At last, the consulting dermatologist suspected an autoimmune blistering skin disease and took a biopsy from peribullous skin for direct immunofluorescence (DIF). DIF revealed linear deposits of IgG (+), IgG1 (+) (Figure 1D), and C3 (++) along the DEJ. No deposits of IgA, IgM, and IgG4 were found. Multiplex ELISA (Euroimmun, Germany) detected the markedly increased level of IgG antibodies against BP180 (9.81), whereas the levels of antibodies against BP230, desmoglein 1, desmoglein 3, type VII collagen, and envoplakin were within normal range (negative level ratio <1). Thus, BP was diagnosed.
Treatment with systemic methylprednisolone intravenously at a single 40 mg dose, intravenous immunoglobulin (1.5 g/kg bwt, the dose was administered within 2 days), amoxicillin (due to secondary bacterial infection of blisters with Streptococcus pyogenes), and a pain reliever (paracetamol) were introduced. A very fast improvement of skin condition was observed during the treatment. After a 5-day hospital stay, our patient was discharged home, and systemic treatment with oral prednisolone and amoxicillin was continued. The doses of prednisone were tapered gradually, about 2.5 mg every 2 weeks, and the treatment was discontinued after 6 weeks. Aggravation of the disease when tapering the dose of prednisone was not observed. With total resolution of lesions that left only discreet post-inflammatory discolorations, the boy remains in good condition.