PYREXIA OF UNKNOWN

ORIGINMeera Ladwa

DEFINITION OF PUO Persistent temperatures of >38.3⁰C Of more than 3 weeks duration

Of unknown cause despite 1 week of inpatient investigations

CAUSES Infections (30-40%)-Bacterial (TB, abscesses, endocarditis, osteomyelitis (discitis), Brucella, Histoplasma, Rickettsia)-Viral (HIV, CMV, EBV)-Parasites (malaria, toxoplasma, leishmaniasis, trypanosomiasis)-Spirochaetes (Borrelia, syphilis)-Fungal (candida in the immunosuppressed)

CAUSES Malignancies (20-30%)-Lymphomas

-Leukaemias-Solid organ tumours (renal cell carcinoma, liver mets)

CAUSES Miscellaneous (20-30%)-Collagen vascular diseases (SLE, rheumatic fever, PAN, polymyalgia rheumatica, giant cell arteritis, Wegener’s granulomatosis)-Chronic inflammatory diseases - Crohns, sarcoid, rheumatoid arthritis-Drugs (penicillins, procainamide, isoniazid)-Endocrine (hyperthyroidism, Addison’s)-Inherited (Familial Mediterranean Fever)-Occult haematoma, occult thrombosis

HISTORY-detailed travel and immunisation hx-detailed hx of previous surgery, dental work-occupational exposure or hobbies eg river water, animals, forests-contacts eg with TB-sexual history-drug history-IV drug use, blood transfusions, tattoos, piercings-family history

EXAMINATION Stigmata of infective endocarditis Rashes Lymphadenopathy Joint swellings Night sweats Spinal tenderness Hepato-splenomegaly

INVESTIGATIONS Blood cultures – at least 3 from separate sites

at separate times Culture everything else – urine, sputum, stool.

Culture of lymph node aspirate, bone marrow. Sputum for AFB, tuberculin skin test, IGRA Viral serology CT abdomen MR to look for osteomyelitis/discitis Echo – consider TOE Vasculitis screen – ANA, ESR, RhF, C3/C4 White cell scan, PET scan (occult abscess and

tumours)

CONCLUSIONS PUO can be a diagnostic challenge! Symptoms and signs can be subtle in

the elderly and immunosuppressed Common causes are infections,

malignancies, and collagen vascular diseases

Remember to go back to the beginning; history and examination will inform appropriate investigations