Neutrophilic dermatosis: a new skin manifestation and novel pathogenic variant in a rare autoinflammatory disease.

Sideroblastic anaemia, B-cell immunodeficiency, periodic fever and developmental delay (SIFD) is caused by mutations of TRNT1, an enzyme essential for mitochondrial protein synthesis, and has been reported in 23 cases. A 6-month-old girl was evaluated with recurrent fever, failure to thrive, skin lesions and anaemia. She received blood transfusions and empirical antibiotics. Skin lesions, previously interpreted as insect bites, consisted of numerous firm asymptomatic erythematous papules and nodules, distributed over trunk and limbs. Skin histopathology revealed an intense dermal neutrophilic infiltrate extending to the subcutaneous, with numerous atypical myeloid cells, requiring the diagnosis of leukaemia cutis, to be ruled out. Over the follow-up, she developed herpetic stomatitis, tonsillitis, lobar pneumonia and Metapneumovirus tracheitis, and also deeper skin lesions, resembling panniculitis. Hypogammaglobulinaemia was diagnosed. An autoinflammatory disease was confirmed by whole exome sequencing: heterozygous mutations for TRNT1 NM_182916 c.495_498del, p.F167Tfs * 9 and TRNT1 NM_182916 c.1246A>G, p.K416E. The patient has been treated with subcutaneous immunoglobulin and etanercept. She presented with developmental delay and short stature for age. The fever, anaemia, skin neutrophilic infiltration and the inflammatory parameters improved. We describe a novel mutation in SIFD and the first to present skin manifestations, namely neutrophilic dermal and hypodermal infiltration.

Hereditary deficiency of the third component of complement in a child with fever, skin rash, and arthralgias: response to transfusion of whole blood.

A previously well 34-month-old male presenting with fever, skin rash, and arthralgias was found to lack C3 by immunochemical (undetectable) and hemolytic (1% normal) assays. No infectious agent could be demonstrated. Protein levels of Clq. C4, C5, properdin, and C3b-INA and hemolytic activities of complement components C1 to C9 except C3 were normal or elevated; total hemolytic complement activity was 13% of normal and was reconstituted by purified C3. Properdin factor B was 702 (normal 175 to 275) mug/ml, and was not cleaver upon addition of zymosan or cobra venom factor. The serum had normal immune adherence activity, but was deficient in ability to opsonize Candida albicans for uptake and Escherichia coli for killing by neurophils, generate neutrophil chemotactic factors and inhibit the growth of E. coli; these activities were restored by purified C3. A transfusion of 320 ml 1-hour-old normal whole blood on the fifty-second day resulted in transitory elevation of the C3 level to 25 mg/dl with a fall-off (approximately 2 1/2% per hour) to undetectable levels by 69 hours; it was followed by disappearance of the skin rash and arthralgias and return to normal of the previously elevated temperature and CRP levels. C3 levels in family members (seven of 24 half-normal), lack of anti-C3 activity, normal C3b-INA levels and a normal rate of catabolism of transfused C3 indicated that the deficiency was inherited with autosomal codominance and involved decreased synthesis of C3. Thus, this child is a unique individual with inherited C3 deficiency presenting with absence of repeated infections, whose symptoms of fever, skin rash, and arthralgia were abated by whole blood transfusion.