Focal ¹⁸F-FDG uptake in bone marrow on PET/CT in a patient with JAK2 mutation without overt myeloproliferative neoplasm

Excerpt

A 58-year-old female diagnosed with early stage esophageal carcinoma in our hospital underwent endoscopic resection by endoscopic submucosal dissection (ESD) in April 2013. ¹⁸F-FDG PET/CT performed immediately prior to the ESD showed focal ¹⁸F-FDG accumulations in the vertebral body of Th8, and vertebral body and arch of L4 with SUV max of 3.98–4.42 (Fig. 1a–c). No masses or osteoclastic lesions were observed. MRI findings of the lesions showed low intensity on T1WI and high intensity on STIR image (Fig. 2a–d). To clarify the cause of the ¹⁸F-FDG accumulation in the bone, we performed bone biopsy from the vertebral arch of L4. Histopathological findings revealed hypercellular marrow (80 % cellularity) and increases in number and size of megakaryocytes, most of which were in maturated form with hyperlobulated nuclei, which are usually found in cases with myeloproliferative neoplasm (MPN) (Fig. 3a, b). Reticulin fibrosis of marrow was observed minimally by Gitter staining (Fig. 3c), and collagen fibrosis was not observed. In contrast, laboratory workup for peripheral blood showed no abnormality: WBC 6,920/μL (stab 0.0 %, seg 61.0 %, lymph 30.0 %, mono 6.0 %, eosino 1.5 %, and baso 1.5 %), RBC 452 × 10⁴/μL, Hb 14.1 g/dL, Ht 40.6 %, PLT 33.3 × 10⁴/μL, reticulocytes 1.2 %, LDH 229 U/L, VB12 351 mg/dL, and NAP score 223. Bone marrow biopsy subsequently performed from the left iliac bone showed normocellular marrow, but the number of megakaryocytes was also increased (Fig. 3d). Furthermore, JAK2 V617F mutation was detected in the bone marrow sample by real-time qualitative PCR with a sensitivity of more than 2 % of all alleles. G-banding showed normal diploid karyotype, and BCR–ABL translocation was not detected by FISH analysis. 5 months after the first visit, her laboratory data of peripheral blood was within the normal range, and ¹⁸F-FDG PET/CT also showed similar ¹⁸F-FDG accumulation in the bone, without new lesions. We will continue to follow her progress carefully.

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