FUO (DR. C) Flashcards
What is the definition of fever of unknown origin (FUO) in children?
A temperature >38°C (100.4°F) documented by a healthcare provider, with no identified cause after at least 8 days of evaluation.
What differentiates fever without a source (FWS) from FUO?
The duration of fever; FWS can progress to FUO if no cause is found after 7 days of evaluation.
What are the main categories of causes of FUO in children?
Infectious, rheumatologic, autoinflammatory, oncologic, neurologic, genetic, factitious, and iatrogenic processes.
What is the common presentation of FUO in children?
Atypical presentations of common diseases, often requiring prolonged observation for diagnosis.
What are common infectious causes of FUO in children in the United States?
Bacterial enterocolitis (e.g., salmonellosis), tuberculosis, rickettsial diseases, syphilis, Lyme disease, cat-scratch disease, atypical viral diseases (e.g., adenovirus, EBV, CMV), and others.
What are common autoimmune causes of FUO?
Juvenile idiopathic arthritis (JIA), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), and Kawasaki disease.
What are some diagnostic clues for drug fever?
Sustained fever without other symptoms, resolving within 72 hours of drug discontinuation (except in some cases like iodides).
What types of infections are more common causes of FUO in low and middle-income settings?
Primarily infectious diseases, due to a higher burden of infections and limited advanced diagnostic techniques.
What historical factors are important in evaluating FUO?
Travel history, exposure to animals, dietary habits, medication history, genetic background, and family history.
What should be documented in suspected cases of factitious fever?
The presence and pattern of fever, often requiring prolonged hospital observation and possibly electronic or video surveillance.
What are the leading causes of classic FUO?
Cancer, infections, inflammatory conditions, undiagnosed causes, and habitual hyperthermia.
What is the definition of healthcare-associated FUO?
A fever ≥38°C (100.4°F) lasting >1 week, not present or incubating on admission.
What are common causes of immune-deficient FUO?
Mostly infections, with a documented cause in only 40–60% of cases.
What is the definition of HIV-related FUO?
A fever ≥38°C (100.4°F) lasting >3 weeks in outpatients or >1 week in inpatients, with confirmed HIV infection.
What are the main diagnostic tools for FUO?
Thorough history, physical examination, screening laboratory tests, and imaging studies guided by clinical findings.
What is pseudo-FUO?
Successive episodes of benign, self-limited infections perceived as one prolonged fever episode.
How can pseudo-FUO be diagnosed?
By identifying afebrile periods between febrile episodes and potentially keeping a fever diary.
What is a key feature of drug-induced fever?
It resolves after discontinuation of the drug, typically within 72 hours.
What are common connective tissue diseases associated with FUO?
Juvenile idiopathic arthritis (JIA) and systemic lupus erythematosus (SLE).
What is the role of PCR in diagnosing FUO?
Improved detection of infectious and autoimmune conditions, reducing the number of undiagnosed FUO cases.
What is the significance of the absence of sweat during fever?
“It suggests dehydration (vomiting
What condition is indicated by chorioretinitis?
“It suggests CMV
What are potential causes of proptosis in a child?
“Orbital tumor
What do nail-fold capillary abnormalities suggest?
“They are associated with connective tissue diseases such as juvenile dermatomyositis and systemic scleroderma.”
What might failure of pupillary constriction indicate in a child with FUO?
“Hypothalamic dysfunction due to absence of the sphincter constrictor muscle.”
What findings might suggest familial dysautonomia in a child with FUO?
“Lack of tears
What conditions might hyperactive deep tendon reflexes indicate?
“Thyrotoxicosis as a cause of FUO.”
What does generalized muscle tenderness suggest?
“Dermatomyositis
What is indicated by point tenderness over a bone?
“Occult osteomyelitis or bone marrow invasion from neoplastic disease.”
What laboratory test results suggest inflammation in FUO evaluation?
“An ESR >30 mm/hr or elevated CRP indicates inflammation.”
What might polymicrobial bacteremia suggest?
“Factitious infection
Why are anaerobic blood cultures rarely used in FUO evaluation?
“Anaerobic infections are rare; cultures are only done if anaerobic infection is suspected.”
What does an absolute neutrophil count (ANC) of <5,000/μL indicate?
“It provides evidence against bacterial infections except typhoid fever.”
What is the role of imaging studies in FUO diagnosis?
“They help detect abscesses
When should empirical antimicrobial therapy be avoided in FUO?
“It should be avoided unless there is clear evidence of infection.”
What is the prognosis for children with FUO compared to adults?
“Children generally have a better prognosis
What is the value of PET-CT or MRI in FUO evaluation?
“These imaging studies help localize occult tumors or abscesses without surgical exploration.”
What findings on ophthalmoscope examination might indicate connective tissue diseases?
“Nail-fold capillary abnormalities observed with immersion oil or jelly.”
What should be done if no clinical clues emerge from history or examination in FUO?
“Surveillance and repeated reevaluations should be performed to detect new findings.”
What findings on bone marrow examination might indicate FUO causes?
“Leukemia
What is the first-line imaging modality for FUO evaluation?
“Total-body CT or MRI with contrast is usually the first choice.”
What laboratory test should always be included in initial FUO evaluation?
“Complete blood count (CBC) with WBC differential and urinalysis.”
What might recurrent oral candidiasis suggest in a child with FUO?
“Disorders of the immune system
What conditions are suggested by hyperemia of the pharynx with or without exudate?
“Streptococcal infection
Which physical finding is associated with sinusitis in patients with fever of unknown origin?
“Sinus tenderness”
What diagnosis is suggested by nodules and reduced pulsations of the temporal artery?
“Temporal arteritis”
What condition can cause ulceration in the oropharynx in patients with fever of unknown origin?
“Disseminated histoplasmosis
What is the diagnosis when a patient with fever of unknown origin has a tender tooth?
“Periapical abscess
What is a possible diagnosis in a patient with loose teeth and fever of unknown origin?
“Langerhans cell histiocytosis
What might choroid tubercles in the fundi or conjunctivae indicate?
“Disseminated granulomatosis*”
What condition is suggested by petechiae or Roth spots in patients with fever of unknown origin?
“Endocarditis”
What is indicated by thyroid enlargement or tenderness in fever of unknown origin?
“Thyroiditis”
What diagnosis is suggested by a murmur and fever of unknown origin?
“Infective or marantic endocarditis”
What does relative bradycardia suggest in fever of unknown origin?
“Typhoid fever
What could enlarged iliac crest lymph nodes and splenomegaly indicate in fever of unknown origin?
“Lymphoma
What condition is associated with an audible abdominal aortic or renal artery bruit in fever of unknown origin?
“Large vessel vasculitis such as Takayasu arteritis”
What is the diagnosis when costovertebral tenderness is present in fever of unknown origin?
“Chronic pyelonephritis
What might perirectal fluctuance or tenderness indicate in fever of unknown origin?
“Abscess”
What diagnosis is suggested by prostatic tenderness or fluctuance in fever of unknown origin?
“Abscess”
What could a testicular or epididymal nodule indicate in fever of unknown origin?
“Periarteritis nodosa
What is the diagnosis when spinal tenderness is observed in fever of unknown origin?
“Vertebral osteomyelitis”
What does paraspinal tenderness suggest in fever of unknown origin?
“Paraspinal collection”
What is the diagnosis associated with deep venous tenderness in fever of unknown origin?
“Thrombosis or thrombophlebitis”
What condition is indicated by pseudoparesis in fever of unknown origin?
“Syphilitic bone disease”
What might petechiae, splinter hemorrhages, or subcutaneous nodules indicate in fever of unknown origin?
“Vasculitis
