Good's syndrome is a very rare form of adult-onset primary immunodeficiency in which the development of thymoma and recurrent infections involving various systems cause significant morbidity and mortality. The diagnosis rests on the identification of hypogammaglobulinemia and other associated laboratory findings and the prognosis strongly depends on a timely diagnosis.
The clinical presentation of Good's syndrome (GS) starts during adulthood, most commonly in the 4th or 5th decade of life, with a mean survival rate of 14 years and overall mortality rates of 45-57% according to most recent reports  . Recurrent infections due to bacterial, viral and fungal pathogens are the most important manifestation of Good's syndrome, arising due to extensive hypogammaglobulinemia and lymphopenia of varying severity  . Most notable examples are infections of the sinuses and the respiratory tract by encapsulated bacteria (haemophilus influenzae and streptococcus pneumoniae, as well as klebsiella pneumoniae and pseudomonas aeruginosa) and fungi (pneumocystis jirovecii), cutaneous and urinary tract infections, but also diarrheas caused by giardia lamblia, campylobacter jejuni, cytomegalovirus (CMV) and salmonella spp.   . Moreover, CMV retinitis, mucocutaneous candidiasis, herpes simplex virus (HSV) and human herpesvirus 8 (HHV-8) infections have been described . In rare cases, central nervous system (CNS) infection may be seen . Sinorespiratory infections manifest with a cough, nasal discharge, fever, and headaches, while diarrhea, abdominal pain, cramping and weight loss are typical signs of gastrointestinal infection. The second cardinal feature of Good's syndrome is the presence of a thymoma, and up to 42% of patients have a confirmed diagnosis prior to the onset of infections . In addition, thymomas are associated with a number of autoimmune disorders, and up to 50% of patients present with signs and symptoms of myasthenia gravis, whereas pemphigus, sjögren syndrome, pure red cell aplasia (PRCA) and systemic lupus erythematosus (SLE) have all been identified in patients suffering from this type of immunodeficiency . In up to 10% of patients, hypogammaglobulinemia may be quite severe even after successful removal of thymomas and is the main cause of mortality in this patient group .
Despite the fact that less than 200 patients have been diagnosed with GS so far , an early diagnosis must be achieved in order to reduce the risk of adverse events and prevent more serious infections that can be life-threatening . For this reason, a detailed patient history (including assessment of age) must be obtained in order to identify the recent development of symptoms that may suggest recurrent infections, but laboratory studies are essential during diagnostic workup. A complete blood count (CBC) is mandatory and should be obtained right away, with anemia, leukopenia (either granulocytopenia or lymphopenia) and/or thrombocytopenia being frequently observed . Furthermore, a thorough immunological workup composed of CD4+/CD8+ T cell and B cell counts and a quantitative immunoglobulin assessment will confirm lymphopenia and hypogammaglobulinemia . Because many patients suffer from additional immunological diseases, detection of anti-acetylcholine receptor (AChR) antibodies, anti-Ro/SSA and anti-La/SSB, as well as antinuclear antibodies (ANA) for myasthenia gravis, sjögren syndrome and SLE, respectively, should be performed. Bone marrow aspiration, as a last resort, can reveal markedly reduced hematopoiesis . On the other hand, the presence of recurrent infections should raise valid suspicion toward disorders of the thymus, and imaging studies, mainly in the form of computed tomography (CT), but also biopsy, are necessary to identify thymoma as an accompanying feature and thus confirm the diagnosis.