Журнал «Здоровье ребенка» 3 (54) 2014

Fever of unknown origin (FUO) was defined by Petersdorf and Beeson in 1961 and has the following criteria:

• body temperature higher than 38,3°С (101°F) on several occasions;
• a disease or pathologic state accompanied by increased body temperature that lasts more than 3 weeks;
• the absence of diagnosis in a patient in spite of diagnostic procedures carried out in hospital for 1 week.

Padiatricians often use a bit other definition according to which FUO has duration more than 2 weeks, when it is impossible to find out a diagnosis even after hospital examination. However, despite some differences of the FUO definitions, it doesn’t include clinical cases of so-called long-term subfebrile states of unknown origin. The matter is that uncertain subfebrile states have a special place in clinical practice and specific diagnostic measurements.

Nowadays it is considered that etiological structure of FUO is the following: infectious diseases (30-40%), tumor processes (20-30%), systemic diseases of connective tissue including vasculites (10-20%) and the other miscellaneous diseases (15-20 %). At the same time, according to existing literature data, doctors don’t succeed in finding of FUO cause in 5-15 % of the all its cases even after comprehensive and detailed examinations.

FUO in children is very urgent and often extremely difficult problem of up-to-date pediatric practice which is indicated in numerous recent articles in leading domestic and foreign serial publications.

First of all, such situation is caused by utterly wide range of various FUO reasons. Apart from that, the increase of body temperature in such cases, as a rule is the only or the only evident clinical sign, at least, in debut of disease development, which is initially diagnosed as FUO.

For the purpose of diagnostic search optimization in the presence of FUO in a child we suggest considering each disease, which can mask as this syndrome, under the scheme including the following items:

• specific anamnestic features;
• except fever, the other typical clinical symptoms (“hallmarks”), whose spectrum and intensity depend on disease stage;
• characteristic laboratory signs;
• necessary instrumental medical investigations;
• necessary subspecialty consultations;
• additional useful information about nosological form.

According to the mentioned above scheme the description of the most widespread in pediatric practice infectious and oncological diseases, which manifest as FUO, is represented in the first part of this article. So, the information about such infectious diseases as tuberculosis, abscesses of abdominal cavity and retroperitoneal space, osteomyelitis, acute or subacute otitis media, renal infection, tick-borne borreliosis, cat-scratch disease, brucellosis, ornithosis, infectious mononucleosis, acquired cytomegalovirus infection, HIV-infection, malaria, toxoplasmosis is stated here. Lymphogranulomatosis (Hodgkin's disease), acute leucosis, nephroblastoma, which refer to oncological diseases, are described as well.

We propose the concept of diagnostic search in case of FUO which bases on step-by-step elimination or revealing of its possible causes, where each subsequent phase will be determined by the result of the previous one. Each particular case of FUO requires individual algorithm of diagnostic search providing for purposeful medical examination with help of the most informative methods for this clinical situation. The optimum way for clarification of FUO nature presupposes the detection of additional clinical or laboratory signs during physical examination or routine laboratory analyses. It permits to narrow the range of suspected diseases and to ensure that the patient with FUO would be examined only by necessary medical specialists and undergo selective additional examinations. Succession in prescription of different special examinations will be determined by the following factors: kind of detected additional signs, information value of diagnostic measures, their accessibility and cost.