Diagnosis of solitary eosinophilic granuloma by CT, MRI, and 18F-FDG PET/CT: two clinical cases

This paper presents two clinical cases of eosinophilic granuloma of bone diagnosed by CT, MRI, and 18F-FDG PET/CT. In both cases the patients were admitted to the clinic with suspected primary malignant bone tumor and the diagnosis of a solitary eosinophilic granuloma was made based on the results of comprehensive radiological diagnostic examination and histological verification. Solitary eosinophilic granuloma of bone is an infrequent condition, occurring in less than 1% of cases of skeletal tumor masses. The most common eosinophilic granuloma is found in the parietal and frontal bones of the skull and is an osteolytic volumetric mass that gradually increases in size. Although most bone tumors can be detected by radiography, computed tomography is preferred, primarily because of its superior ability to detect cortical bone destruction. The diagnostic accuracy of computed tomography and magnetic resonance imaging may be different. The combined use of radiological and radionuclide methods allows us to narrow the spectrum of differential diagnosis. Unfortunately, relatively low specificity of existing radiological diagnostic studies in most cases does not allow to establish a precise diagnosis, and biopsy with subsequent pathological examination remains the method of choice. These clinical observations demonstrate the need to include eosinophilic granuloma in the differential diagnosis when a solitary osteolytic focus is detected.