Case 1 -

Chronic Granulomatous Disease (CGD) Jonathan W. Said UCLA Center for Health Sciences Los Angeles, California

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Clinical History: The patient is a 15 month old boy with fever, upper respiratory tract infection, leukocytosis, and a localized lesion on the right cheek which was biopsied. Stains for organisms (AFB, GMS, PAS, GRAM) were negative. Histologic findings: H&E sections reveal a granulomatous proliferation containing numerous epithelioid type histiocytes forming loose granulomas without necrosis and occasional multinucleated giant cells. There are numerous small lymphocytes as well as plasma cells. Immunohistochemical studies reveal that the majority of small lymphocytes are T-cells staining for CD3 and CD5. Numerous histiocytes stain for CD68 and CD43 stains both components. Case 1 - Figure 1 Case 1 - Figure 2 Case 1 - Figure 3 Case 1 - Figure 4 Case 1 - Figure 5 Discussion: "Diagnosis too easy to miss" This case was perplexing to the pathologists at the referring institution where the biopsy was performed and at first to us until the penny dropped and we obtained further clinical information and were able to confirm the diagnosis of CGD. The histologic features are obvious and require no sophisticated studies. Although uncommon the entity is an important clinical syndrome that needs to be identified. Differential diagnosis: There is a large differential for granulomatous lymphadenitis, some of the more important entities are listed below: Tuberculous lymphadenitis associated with caseation Fungal granulomas (Aspergillosis, Mucormycosis, Candidiasis, Histoplasmosis, Cryptococcosis) Granulomatous microabscesses (Tularemia, Yersinia, Brucellosis, Cat Scratch, Lymphogranuloma) Lymphadenitis due to BCG Atypical mycobacteria (MAC) Spindle cell pseudotumors Toxoplasmosis Leishmaniasis Rheumatoid granulomas Drug reactions including hydantoin Dermatopathic lymphadenitis Rosai Dorfman disease Peripheral T-cell lymphoma lymphoepithelioid variant Discussion: What is CGD? Chronic granulomatous disease (CGD) is a genetically determined primary immune deficiency disorder in which the underlying deficiency is an inability of phagocytes to deal with ingested microorganisms, particularly bacteria and fungi that are catalase positive and do not themselves have a net production of reduced oxygen metabolites such as hydrogen peroxide (Winkelstein, Marino et al. 2000) . Although there are several molecular abnormalities that can cause CGD, they all involve components of the NADPH oxidase of the phagocytic cell (Kono, Rusyn et al. 2000; Segal and Holland 2000) . Clinical features: The clinical features of CGD were only first described in 1957 (Berendes, Bridges et al. 1957) . The majority of patients with CGD are diagnosed before age 5, although about 15% (most with the recessive form of the disease) are diagnosed later. The majority are inherited in an X-linked recessive fashion, and therefore most are male. The most common infection is pneumonia, followed by abscesses and suppurative adenitis. More serious infections include osteomyelitis, cellulitis, and meningitis. Common organism include Staphylococcus, aspergillus, klebsiella, nocardia, and many others. Staphylococcus is the most common cause of skin infections as in this patient. Treatments include interferon gamma, granulocyte transfusions, prophylactic antibiotics, and in patients with the X-linked recessive form of the disease bone marrow transplant has been attempted. Mortality is highest in patients with the X-linked recessive form (21%), and aspergillus pneumonia is the most common cause of death (Winkelstein, Marino et al. 2000) . Molecular basis of CGD: CGD arises from a defect in any of the 4 subunits of NADPH oxidase (Segal, Leto et al. 2000) . When a pathogen is ingested it fuses with secondary granules within the phagocytic vacuole. In patients with CGD NADPH oxidase is unable to generate superoxide anion by transferring electrons from NADPH to molecular oxygen. The superoxide anion is therefore unable to generate other antimicrobial reactive oxygen intermediates such as H202, hydroxyl anion, and peroxy-nitrite anion. There are now mouse knockout models of CGD, which will contribute to understanding of the pathophysiologic defects and new therapies including gene therapy and bone marrow transplants. References: Berendes, H., R. A. Bridges, et al. (1957). "A fatal granulomatosus of childhood: The clinical study of a new syndrome." Minn Med 40: 309-312. Kono, H., I. Rusyn, et al. (2000). "NADPH oxidase-derived free radicals are key oxidants in alcohol-induced liver disease." J Clin Invest 106(7): 867-72. In North America, liver disease due to alcohol consumption is an important cause of death in adults, although its pathogenesis remains obscure. Despite the fact that resident hepatic macrophages are known to contribute to early alcohol-induced liver injury via oxidative stress, the exact source of free radicals has remained a mystery. To test the hypothesis that NADPH oxidase is the major source of oxidants due to ethanol, we used p47(phox) knockout mice, which lack a critical subunit of this major source of reactive oxygen species in activated phagocytes. Mice were treated with ethanol chronically, using a Tsukamoto-French protocol, for 4 weeks. In wild-type mice, ethanol caused severe liver injury via a mechanism involving gut-derived endotoxin, CD14 receptor, production of electron spin resonance-detectable free radicals, activation of the transcription factor NF-kappaB, and release of cytotoxic TNF-alpha from activated Kupffer cells. In NADPH oxidase-deficient mice, neither an increase in free radical production, activation of NF-kappaB, an increase in TNF-alpha mRNA, nor liver pathology was observed. These data strongly support the hypothesis that free radicals from NADPH oxidase in hepatic Kupffer cells play a predominant role in the pathogenesis of early alcohol-induced hepatitis by activating NF-kappaB, which activates production of cytotoxic TNF-alpha. Segal, B. H. and S. M. Holland (2000). "Primary phagocytic disorders of childhood." Pediatr Clin North Am 47(6): 1311-38. Primary phagocytic disorders are rare and usually first manifest during childhood. A phagocytic disorder should be considered in patients with unusually severe or recurrent infections by common pathogens or an infection by certain opportunistic pathogens. Common manifestations of primary phagocytic disorders include recurrent soft-tissue infections requiring incision and drainage, severe dental infections leading to premature tooth loss, recurrent pneumonias, and perirectal infections. Primary phagocytic disorders are caused by defects of neutrophil number or function, and the latter, in turn, can be divided into disorders of oxidative and nonoxidative pathways. Certain phagocytic disorders have unique characteristics apart from the immune defect that may facilitate diagnosis. Early diagnosis of phagocytic disorders can be life-saving or lead to a significant reduction in morbidity and relies on a compatible clinical (or family) history and appropriate laboratory diagnostic studies. Key principles of management of such patients involve early recognition and aggressive treatment of infections and appropriate surgical debridement of localized disease. Prophylactic antibiotics, BMT, and the use of exogenous cytokines, such as IFN-gamma and G-CSF, are appropriate for specific phagocytic disorders. Gene therapy is a promising strategy for several of the phagocytic disorders. Segal, B. H., T. L. Leto, et al. (2000). "Genetic, biochemical, and clinical features of chronic granulomatous disease." Medicine (Baltimore) 79(3): 170-200. The reduced nicotinamide dinucleotide phosphate (NADPH) oxidase complex allows phagocytes to rapidly convert O2 to superoxide anion which then generates other antimicrobial reactive oxygen intermediates, such as H2O2, hydroxyl anion, and peroxynitrite anion. Chronic granulomatous disease (CGD) results from a defect in any of the 4 subunits of the NADPH oxidase and is characterized by recurrent life-threatening bacterial and fungal infections and abnormal tissue granuloma formation. Activation of the NADPH oxidase requires translocation of the cytosolic subunits p47phox (phagocyte oxidase), p67phox, and the low molecular weight GT-Pase Rac, to the membrane-bound flavocytochrome, a heterodimer composed of the heavy chain gp91phox and the light chain p22phox. This complex transfers electrons from NADPH on the cytoplasmic side to O2 on the vacuolar or extracellular side, thereby generating superoxide anion. Activation of the NADPH oxidase requires complex rearrangements between the protein subunits, which are in part mediated by noncovalent binding between src-homology 3 domains (SH3 domains) and proline-rich motifs. Outpatient management of CGD patients relies on the use of prophylactic antibiotics and interferon-gamma. When infection is suspected, aggressive effort to obtain culture material is required. Treatment of infections involves prolonged use of systemic antibiotics, surgical debridement when feasible, and, in severe infections, use of granulocyte transfusions. Mouse knockout models of CGD have been created in which to examine aspects of pathophysiology and therapy. Gene therapy and bone marrow transplantation trials in CGD patients are ongoing and show great promise. Winkelstein, J. A., M. C. Marino, et al. (2000). "Chronic granulomatous disease. Report on a national registry of 368 patients." Medicine (Baltimore) 79(3): 155-69. A registry of United States residents with chronic granulomatous disease (CGD) was established in 1993 in order to estimate the minimum incidence of this uncommon primary immunodeficiency disease and characterize its epidemiologic and clinical features. To date, 368 patients have been registered; 259 have the X-linked recessive form of CGD, 81 have 1 of the autosomal recessive forms, and in 28 the mode of inheritance is unknown. The minimum estimate of birth rate is between 1/200,000 and 1/250,000 live births for the period 1980-1989. Pneumonia was the most prevalent infection (79% of patients; Aspergillus most prevalent cause), followed by suppurative adenitis (53% of patients; Staphylococcus most prevalent cause), subcutaneous abscess (42% of patients; Staphylococcus most prevalent cause), liver abscess (27% of patients; Staphylococcus most prevalent cause), osteomyelitis (25% of patients; Serratia most prevalent cause), and sepsis (18% of patients; Salmonella most prevalent cause). Fifteen percent of patients had gastric outlet obstruction, 10% urinary tract obstruction, and 17% colitis/enteritis. Ten percent of X-linked recessive kindreds and 3% of autosomal recessive kindreds had family members with lupus. Eighteen percent of patients either were decreased when registered or died after being registered. The most common causes of death were pneumonia and/or sepsis due to Aspergillus (23 patients) or Burkholderia cepacia (12 patients). Patients with the X-linked recessive form of the disease appear to have a more serious clinical phenotype than patients with the autosomal recessive forms of the disease, based on the fact that they are diagnosed significantly earlier (mean, 3.01 years of age versus 7.81 years of age, respectively), have a significantly higher prevalence of perirectal abscess (17% versus 7%), suppurative adenitis (59% versus 32%), bacteremia/fungemia (21% versus 10%), gastric obstruction (19% versus 5%), and urinary tract obstruction (11% versus 3%), and a higher mortality (21.2% versus 8.6%).