Presentation
Left hip and lower abdominal pain.
Patient Data
Synovial mass-like thickening centered on the left hip joint extending into the upper thigh with erosion of both the femoral head and acetabulum. This has intermediate T1 signal and intermediate-to-low T2 signal with blooming on susceptibility sequence. Acetabular subchondral cyst also present. Superior femoral head subchondral fracture and articular surface flattening with marrow edema extending into the femoral neck.
Tenosynovial giant cell tumor was the primary differential diagnosis. The patient was planned to proceed to debulking and arthroplasty. Templating x-rays were performed.
Left hip joint space narrowing. Permeative appearance of the medial femoral head with bone destruction. Superior femoral head flattening. Lucency at the medial and superior acteabulum.
Pelvic surgical clips.
Hip arthroplasty template markers.
Histopathology
Microscopic: the sections of the synovium show features in keeping with pigmented villonodular synovitis. The lesion is dominated by sheets of foamy histiocytic cells which are admixed with smaller bland inflammatory cells and plasma cells. There are areas within the lesion within which rounded mononuclear cells and some collections of multinucleated giant cells are present. Some foamy histiocytes, some containing cytoplasmic pigment. Occasional Touton giant cells are present. Pseudoglandular spaces are present within the solid regions, where a cleft–like spaces are lined by cuboidal, synovial-like cells. The surface has a partially villous/papillary architecture. There is no polarisable foreign material. Adjacent skeletal muscle is included. There is no evidence of cytologic atypia. Mitotic activity is not identified. There is no malignancy.
Diagnosis: left hip synovium and mass: Pigmented villonodular synovitis.
Case Discussion
This is a case of diffuse tenosynovial giant cell tumor, previously known as pigmented villonodular synovitis (PVNS), of the hip. On MRI, the low T2 signal and blooming on the T2* sequence are characteristic findings.
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