T2-weighted Hypointense Tumors and Tumor-like Lesions

Abstract

Most musculoskeletal tumors are hyperintense on T2-weighted images. However, some T2-weighted hypointense tumors and tumor-like lesions are encountered in everyday clinical practice. We explore the spectrum of such T2 hypointense tumors and tumor mimickers that can arise from (1) the bones, presenting as diffuse processes or focal lesions; (2) the joints including diffuse or focal synovial disorders, loose bodies, or substance depositions; and (3) soft tissues, comprising T2 hypointense tumors and tumor mimickers (those that contain abundant fibrous tissue, mineralization, or hemosiderin deposits). Appropriate magnetic resonance imaging sequence selection is required to identify and characterize these lesions confidently when imaging musculoskeletal tumors.

Diffuse-Type Tenosynovial Giant Cell Tumor: What Are the Important Findings on the Initial and Follow-Up MRI?

“…On MRI, synovitis is characterized by increased water content and includes numerous inflammatory cells, granulation tissue, and abundant blood vessels, resulting in high SI on T2WI with robust contrast enhancement [48]. In the late stage, synovial fibrosis gradually evolves, manifesting as a turbid fluid showing hypointensity with poor contrast enhancement [56]. Additionally, rice bodies, which are multiple loose bodies of approximately the same size and shape, represent a characteristic finding in rheumatoid arthritis (Figure 13) [56].…”

“…In the late stage, synovial fibrosis gradually evolves, manifesting as a turbid fluid showing hypointensity with poor contrast enhancement [56]. Additionally, rice bodies, which are multiple loose bodies of approximately the same size and shape, represent a characteristic finding in rheumatoid arthritis (Figure 13) [56].…”

“…FTS is a rare benign tumor commonly found in the hands, wrists, and feet, similar to TSGCT [56]. Despite the similarities in MRI features between FTS and TSGCT, Ge et al [22] identified key differences.…”

“…In contrast, TSGCT predominantly displays granular or separated low SI, located near the periphery of the tumor, as foam cells that can engulf hemosiderin, resulting in patchy or nested distribution around the lesion. The morphology of the two types also differs: FTS tumors are predominantly round or ovoid (Figure 15), while TSGCT tumors are cast-molding and lobulated [22,56,60]. Although both FTS and TSGCT have been reported to cause absorption of adjacent bone, only a few cases of FTS with bone erosion have been described [61].…”

Post-traumatic myositis ossificans: a benign lesion that simulates malignant bone and soft tissue tumours

“… 16 As the tumour wraps around the bone, a cleft may be seen partially separating the exophytic part of the tumour from the cortex; the so-called ‘cleft sign’. 40 The cortex appears thickened but without aggressive periosteal reaction. 39 CT and MRI can confirm the presence of a broad-based thick stalk and central mineralization allowing distinction from MO in doubtful cases.…”