Duffy phenotyping and FY*B-67T/C genotyping as screening test for benign constitutional neutropenia

ABSTRACT Objective: Low levels of neutrophils can be an intrinsic condition, with no clinical consequences or immunity impairment. This condition is the benign constitutional neutropenia (BCN), defined as an absolute neutrophils count (ANC) ≤2000 cells/mm. Diagnosis of BCN is of exclusion where patients are submitted to blood tests and possibly to invasive diagnostic search until secondary causes of neutropenia are ruled out. The natural history of the disease suggests benign evolution and Brazilian study showed an overall frequency of 2.59%. The main mechanisms include reduced neutrophil production, increased marginalization, extravasation to the tissues and immune destruction. Genetic studies showed strong association between the single nucleotide variant rs2814778 located on chromosome 1q23.2 in the promoter region of the atypical chemokine receptor 1 (Duffy blood group system) gene (ACKR1, also termed DARC) and BCN. The aim of this study is to evaluate FY phenotypes and genotypes including the analysis of the rs2814778 SNP in Brazilian patients with BCN in order to determine an effective diagnostic tool, allowing reassurance of the patient and cost reduction in their care. Methods: Case control study, with 94 individuals (18 patients and 76 controls). Phenotyping was performed by gel test and genotyping was performed by PCR-RFLP. Results: White blood cell (WBC) and absolute neutrophils (AN) counts showed lower levels in patients compared to controls. In the patient group 83.3% were genotyped as FY*B/FY*B. The SNP rs2814778 (-67T > C) was identified in 77.8% of the patients genotyped as FY*B-67C/FY*B-67C. In the control group, 72.7% were homozygous for the wild type and 23.3% were heterozygous. Conclusion: This study reinforces that FY phenotyping and genotyping can be used to detect most people with BCN, avoiding excessive diagnostic investigation. Besides, this procedure may reduce health costs and be reproductible in clinical practice.

Hiperplasia angiolinfoide como causa de eosinofilia / Angiolymphoid hyperplasia as the cause of eosinophilia

A hiperplasia angiolinfoide (Hale e doença de Kimura são duas entidades que podem se manifestar como nódulos, placas ou pápulas, de localização predominante em face, região retroauricular e cervical. São causas raras de eosinofilia e ainda há muita discussão em torno de suas etiopatogenias. Para alguns autores trata-se de duas patologias distintas enquanto para outros são manifestações diferentes da mesma doença. O presente artigo relata o caso de um paciente asiático que apresentava história de prurido generalizado há um ano, acompanhado de pápulas em membros e nódulo de aproximadamente 5 cm de diâmetro em região retroauricular direita com aumento progressivo. O hemograma apresentava leucocitose às custas de eosinofilia. Os achados sugerem uma superposição entre as duas patologias, pois clinicamente são sugestivos de doença de Kimura, mas a histopatologia e imuno-histoquímica confirmaram a origem endotelial da lesão, sendo compatível com Hale. Os autores destacam a raridade do caso como causa de eosinofilia, assim como alertam para a dificuldade do diagnóstico e da diferenciação entre as duas patologias.

Angiolymphoid hyperplasia (Hale) and Kimura disease are two entities that can manifest as subcutaneous nodules, plaques, or papules, and the predominant localization is face, retroauricular and cervical region. They are rare causes of eosinophilia and there is discussion regarding their etiopathogenesis. Some authors propose that these two diseases are truly individual, but others say that they are separate points on a single spectrum. This article is a case report of an asian patient that showed a one year duration of generalized pruritus, with papules on the limbs and a 5 centimeter nodule on the right retroauricular region with slow progression of the size. The hemogram showed leucocitosis with eosinophilia. These findings suggest an overlap between these two diseases, they are clinically suggestive of Kimura disease diagnosis, but the histopathology with HE and immunohistochemistry confirmed the endothelial origin of the lesion that was compatible with Hale. The authors emphasize the rarity of the case as the cause of eosinophilia, also alert for the challenge of the diagnosis and distinction between these two diseases.