The bacilli Calmette-Guérin (BCG) vaccine is administered to all newborns in countries where tuberculosis is endemic. Immunocompromised hosts, namely patients with human immunodeficiency virus infection or primary immunodeficiencies, are especially prone to serious complications from this vaccine. We report three cases of BCG disease in children with primary immunodeficiencies: one with a partial recessive interferon-γ receptor 1 deficiency, who developed BCG dissemination; and two relatives with ZAP70 deficiency, a severe combined immunodeficiency, both of whom presented with regional and distant BCG disease. All had severe axillary lymphadenitis. These clinical cases underline the importance of considering the diagnosis of immunodeficiency in a child with severe axillary lymphadenitis after BCG vaccination and of disseminated BCG disease in an immunodeficient child in the appropriate clinical setting. Moreover, BCG vaccination should be delayed in every newborn with a family history of primary immunodeficiency until the condition has been ruled out.

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Vaccine failure is a rare condition and the need to investigate a primary immunodeficiency is controversial. We present the case of a 4-year-old boy, with complete antipneumococcal vaccination, who had necrotising pneumonia with pleural effusion and severe pancytopaenia with need for transfusion. A vaccine-serotypeStreptococcus pneumoniaewas isolated in the blood culture. On follow-up, detailed medical history, laboratory and genetic investigation led to the diagnosis of X linked dyskeratosis congenita. Dyskeratosis congenita is an inherited disorder that causes shortening or dysfunction of telomeres, affecting mainly rapidly dividing cells (particularly in the skin and haematopoietic system). It leads to bone marrow failure, combined immunodeficiency and predisposition to cancer. The confirmation of this diagnosis allows genetic counselling and medical monitoring of these patients, in order to detect early complications such as bone marrow aplasia or malignancies.

Peroxisome biogenesis disorders are related to a spectrum of genetic diseases that range from severe Zellweger syndrome to milder infantile Refsum disease. Zellweger syndrome is characterised by dysmorphic features, severe hypotonia, seizures, failure to thrive, liver dysfunction and skeletal defects. Increased levels of very long chain fatty acids are the biochemical hallmark and the most common mutations found in the PEX1 gene. We report an unusual presentation of Zellweger syndrome in a 2-month-old female infant with severe malnutrition, opportunistic infections, lymphopaenia and a small thymic shadow on chest radiography. With this clinical picture, an initial hypothesis of primary immunodeficiency was considered. It was later confirmed to not be the case. On follow-up, global developmental delay, bilateral optic nerve atrophy and moderate bilateral sensorineural deafness grade II were documented. There were no further infectious complications and we concluded malnutrition was the cause of the infant's immunocompromised state.

Patients with antibody deficiencies are more prone to develop acute neutropenic episodes even during immunoglobulin replacement. The aims of this study were to evaluate the presence of acute neutropenia in 42 patients with primary antibody immunodeficiencies, currently receiving intravenous immunoglobulin (IVIG), and to describe the clinical and laboratory findings during neutropenic episodes. Of all patients, 10 (23.8%) presented acute neutropenia (absolute neutrophil count <1500 cells/mm3) during follow up (mean of 6.4 yr). The absolute neutrophil count ranged from 71 to 1488 cells/mm3. Neutropenia was not clearly associated with antibiotic prophylactic therapy or immunoglobulin levels, while infections were associated with neutropenia in the majority of episodes. Most acute neutropenia episodes were mild or moderate, except in CVID patients who present more severe neutropenia. Although IVIG may have contributed to reducing the severity of neutropenia, it does not prevent its occurrence in all patients. In conclusion, primary immunodeficient patients, even submitted to IVIG replacement therapy, must be regularly evaluated for neutropenia in order to minimize the risk of infections and its appropriate approach.