18 F-FDG-avid Myelophthisis : A Caveat Unveiling Occult Signet-ring Cell Gastric Carcinoma

Disseminated 18 F-FDG-avid intraosseous lesions and clumps of malignant signet-ring cells on subsequent bone marrow aspirate were detected upon investigation of a 58-year-old man with intolerable bone pain, normocytic anemia, and elevated serum alkaline phosphatase. Immunohistochemistry and gastroscopic biopsy confirmed mucin-rich signet-ring cell adenocarcinoma [signet-ring cell gastric carcinoma (SRGC)]. Intriguingly, synchronous bone secondaries from SRGC tend to be hypermetabolic, regardless of the primary tumor 18 F-FDG-negativity, insinuating a reverse heterogeneity of tumor molecular biology. The identification of 18 F-FDG-avid myelophthisis on the setting of bone pain constitutes a caveat for suspicion of cancerous lesions from SRGC and should urge for bone marrow biopsy to improve treatment implications.