This page is dedicated to organizing various examples of standardized exam questions whose answer is chronic granulomatous disease. While this may seem a odd practice, it is useful to see multiple examples of how chronic granulomatous disease will be characterized on standardized exams (namely the boards and the shelf exams). This page is not meant to be used as a tradition question bank (as all of the answers will be the same), however seeing the classic “test” characterization for a disease is quite valuable.
KEY CHARACTERISTICS OF THIS CONDITION (ON EXAMS)
When it comes to standardized exams, each condition has its own “code” marked by key buzzwords, lab findings, clues, etc. If you are well versed in this code you will be able to more quickly identify the condition that is being discussed, and get the right answer on the exam you are taking. Below is the “code” for chronic granulomatous disease.
- Recurrent infections: typically of the skin/respiratory tract but can also inlcude lymph nodes and liver
- Often infected with catalase positive organisms: Staphylococcus aureus, Serrate, Burkholderia, Aspergillus
- Family history of similar symptoms: the history may reveal similar symptoms in a maternal male related to the patient (x-linked condition).
- Infected with catalase positive organisms: Staphylococcus aureus, Serrate, Burkholderia, Aspergillus
- Normal immune cell counts: B-cell, T-cell, neutrophil counts are unaffected
- Diffuse granuloma formation may be detected histologically
- Neutrophils that engulf, but can not kill bacteria: can be appreciated in various way during the workup.
Question # 1
A 2 year old boy is brought to the physician because of a suspicious “boil” on his left arm. His past medical history is notable for 4 past skin infections. He has had a perianal abscess that was treated at age 3 months. Cultures from the abscess grew out Staphylococcus aureus. When he was 8 months old he had a right inguinal lymphadenitis. Last year he had another abscess on his right calf that required surgical drainage. Currently his temperature is 99.0°F. A physical exam shows an indurated and fluctuant mass on the medial aspect of his left arm. The rest of the physical exam is non-contributitory. Laboratory studies are conducted and they reveal normal leukocyte, platelet, B-cell, and T-cell concentrations. What diagnosis could explain this presentation?
Explanation # 1
Re-current cutaneous infections+ catalase positive infection (Staph aureus) + normal leukocyte/platelet/B-cell/T-cell concentrations = chronic granulomatous disease
Question # 2
A 4 year old boy is brought to the pediatrician because he has been experiencing 4 days of painful swelling in his left groin. His mother is also concerned because he has been running a fever during this time. The patients past medical history is notable for 5 pervious episodes of cutaneous abscesses as well as a lung abscess that was caused by Staphylococcus aureus. All of these episodes were treated successfully with abscess drainige and antibiotics. Family history is notable for a maternal uncle who passed away last year from recurrent infections. In the clinic the patient’s temperate is 101.5°F. A physical exam reveals an enlarged, tender, and fluctuant lymph node in the left inguinal area. The rest of the physical exam is non-contributory. Lab results are shown below:
- Hgb: 12.5 g/dL
- Platelets: 350,000/mm³
- Leukocytes: 12,000/mm³
- Neutrophils: 55%
- Bands: 8%
- Lymphocytes: 32%
Fluid is aspirated form the affected lymph node and cultures are pending. What diagnosis could explain this presentation?
Explanation # 2
Re-current cutaneous/respiratory infections + catalase positive organism (Staph aureus) = chronic granulomatous disease
Question # 3
A 5 year old boy is brought to his doctor because he has a week of a fever. He also has a painful and swollen lymph node that is in his groin. Evaluation of this past medical records reveal that this is the 7th time that he has had this type of lymph node swelling. In the past this has been treated with drainage, and a prolonged course of antibiotics. The patient’s past medial history is notable for a pneumonia that occurred at the age of 14 months, which required the placement of a chest tube so that it could be drained. His family history is notable for a maternal uncle who passed away at a young age from recurrent infections. Currently the patient has a temperature of 101.6°F. A physical exam reveals a warm, erythematous light node in the right inguinal area that is tender to palpation. Aspirate form the lymph node is collected and shows that it is filled with bacteria. Cultures grow out Staphylococcus aureus. What is the likely diagnosis in this patient?
Explanation # 3
Recurrent lymph node infection + history of other infections (respiratory) + family history of similar situation + catalase positive organism (Staphylococcus aureus) = chronic granulomatous disease
Question # 4
A 6 year old male has a history of recurrent skin infections that are granulomatous. He also has had a prior episode of Aspergillus pneumonia. He currently undergoes a partial hepatectomy because he has a poorly draining liver abscess that requires urgent treatment. The patient later develops a pneumonia when he is recovering post-operatively. Sputum cultures are collected and they grow out Burkholderia cepacia. What is the likely diagnosis in this patient?
Explanation # 4
Recurrent granulomatous skin infections + respiratory and liver infections + catalase positive organism (Aspergillus and Burkholderia) = chronic granulomatous disease
Question # 5
A 3 year old boy is brought to the hospital to be evaluated given his history of recurrent, severe infections. He has been already hospitalized 4 times with pneumonia since he was born. He also has suffered from multiple skin infections that have required antibiotic treatment to resolve. The patient’s neutrophils are exposed to nitroblue tetrazolium, and fail to turn blue. What is the likely diagnosis in this patient?
Explanation # 5
Re-current pulmonary infections + re-current cutaneous infections + failed nitroblue tetrazolium test (doesn’t turn blue) = chronic granulomatous disease
Question # 6
A 12 yea roll boy has repeated episodes of staphylococcal pneumonia. Peripheral blood neutrophils are collected and incubated with Staphylococcus aureus in a petrie dish. The patient’s neutrophils do not demonstrate a respiratory burst, and do not kill the bacterial cells even though they are able to engulf them. What si the likely diagnosis in this patient?
Explanation # 6
Recurrent episodes of pneumonia + catalase positive organism (Staph species) + neutrophils engulf but don’t kill bacteria with respiratory burst = chronic granulomatous disease
Question # 7
A 45 year old male comes to the hospital because he has had shortness of breath, and a fever for the past 5 days. A gram stain is collected from his sputum that shows many neutrophils that have engulfed gram-positive diplococci. They appear to be missing an enzyme that allows them to initiate the intracellular killing of these organisms. What condition does this patient have?
Explanation # 7
Pneumonia + neutrophils can engulf but not kill bacteria = chronic granulomatous disease
TESTABLE FACTS ABOUT THIS CONDITION (BEYOND ITS IDENTIFICATION)
Many questions on standardized exams go beyond simply recognizing the underlying condition. Often there are specific testable facts regarding some aspect of the disease’s pathophysiology/management/clincial implications that are commonly asked. Some of these are listed below:
- Defect in the NADPH oxidase of phagocytic cells. Leads to impaired killing of catalase-positive organisms (Staphylococcus aureus, Serrate marcescens)
- Impaired respiratory burst will inhibit phagocytic intracellular killing. Neutrophils can engulf but can not kill bacteria.
- Most cases X-linked
How is the diagnosis made:
- The proffered method is to use dihydorhodamine (DHR) flow cytometry: conversion of DHR to rhodamine (fluorescent green compound) is measured. Cells with deficient NADPH oxidase will have decreased fluorescence (which can be detected by flow).
- Another method is the nitroblue tetrazolium (NBT) test: NBT is added to a sample of the patient’s neutrophils. Neutrophils that function properly can reduce the yellow NBT to a dark blue formazan that precipitates within cells. Those with NADPH deficiency can not do this.
Page Updated: 11.21.2016