Metastasizing tenosynovial giant cell tumour, diffuse type/pigmented villonodular synovitis

Abstract

Tenosynovial giant cell tumour, diffuse type, also known under a variety of other terms including diffuse pigmented villonodular synovitis, tends to be locally aggressive and not infrequently can show multiple recurrences. The differential diagnosis with the extremely rare and somewhat controversial malignant variant of tenosynovial giant cell tumour, diffuse type, is challenging due to overlapping radiologic features of these two entities. Malignant tenosynovial giant cell tumour is defined by the presence of overtly malignant sarcomatous areas. We describe a very unusual case of a 63-year-old man affected by tenosynovial giant cell tumour, diffuse type of the knee that, despite absence of morphologic evidence of sarcomatous transformation, developed inguinal lymph node metastases following multiple surgical procedures.

Keywords: Diffuse type; Lymph node; Metastases; Tenosynovial giant cell tumor.

Figure 1

a On magnetic resonance imaging, an heterogeneous multinodular mass was observed on sagittal T1-weighted images (TR/TE: 1,200/120). Dark signal nodules, compatible with hemosiderin deposition, were identified. b On macroscopy a multinodular lesion was evident in the leg and in the thigh showing variegated colour. c, d On haematoxylin and eosin staining the lesion showed synovial-like mononuclear cells without cytologic atypia, admixed with multinucleate giant cells.

Figure 2

a, b The haematoxylin and eosin staining of the inguinal lymph node revealed a metastasis of D-TGCT showing a proliferation of synovial-like mononuclear cells, admixed with multinucleate giant cells and siderophages.