[Analysis of (18)F-FDG PET/CT features and clinical manifestations in one case of subcutaneous lymphomatoid granulomatosis].

This study was aimed to investigate the pathology, MICM classification, PET/CT characteristics and therapeutical experience of subcutaneous soft tissue muscle gap lymphomatoid granulomatosis (LYG) through analysis of a cases of LYG. The pathologic changes of LYG were assayed by using immunohistochemistry method;the immuno-phenotypes were detected by flow cytometry. The nested multiplex PCR was used to detect the expression and mutation of abnormal genes; the real-time fluorescence quantitative PCR was used to detect the EBV-DNA copies. The clinical staging was performed by means of fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT). The results showed that at onset of disease the clinical manifestations of patient presented only a mass in right thigh and swelling of right submandibular lymph nodes. However, PET/CT revealed that the abnormal image in multiple soft tissue accompanied by increasing metabolic activity (SUVmax = 12.8), these pathologic changes were involved in lung, thyroid, lymphonodes and stomach. The right thigh mass biopsy confirmed the histological diagnosis of grade II LYG. The bone marrow smear showed no abnormal tumor cell infiltration, the immunophenotyping detection revealed that the proportion of NK cells increased with phenotypic abnormality, the karyotype was 46, XY[24], the expression and mutation of abnormal gene not could be detected, and the EBV-DNA level was <10(2) copies/ml. After 2 cycles of treatment with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone(R-CHOP), the images of increasing metabolic activity in subcutaneous soft tissue gap disappeared, but the partial increasing metabolism focus could be observed in soft tissue of left knee hollow. The patient achieved partial remission. It is concluded that LYG is an extremely rare hematopoietic malignancy, the incidence rate is very low. Subcutaneous soft tissue muscle gap LYG literature was not reported in domestic and foreign literatures.Its pathogenetic remains unclear. A standard treatment protocol for LYG has not yet been established. PET/CT can find more lesions that not could be found in the clinical examination. The (18)F-FDG PET/CT is an efficient tool for the LYG in diagnosis, staging and treatment. Therefore, increased SUV(max) in FDG-PET may be useful for diagnosis of LYG.