Smooth muscle actin expression in primary bone tumours

Abstract

Alpha isoform of smooth muscle actin (SMA) expression has been reported in giant cell tumour of bone (GCTB) and other benign and malignant bone tumours, but the pattern of SMA expression and the precise nature of SMA-expressing cells in these lesions is uncertain. We determined by immunohistochemistry the expression of SMA and other muscle and vascular markers in normal bone, GCTB and a wide range of primary benign and malignant bone tumours. Cultured stromal cells of GCTB, chondroblastoma (CB), and aneurysmal bone cyst (ABC) were also analysed for SMA expression. SMA was only noted in blood vessels in normal bone. SMA was expressed by mononuclear stromal cells (MSC) cultured from GCTB, ABC and CB. SMA was strongly and diffusely expressed by MSC in non-ossifying fibroma, fibrous dysplasia, and "brown tumour" of hyperparathyroidism. SMA expression was also noted in GCTB, ABC, CB, chondromyxoid fibroma, malignant fibrous histiocytoma of bone and osteosarcoma. Little or no SMA was noted in Langerhans cell histiocytosis, simple bone cyst, Ewing's sarcoma, osteoblastoma, osteoid osteoma, enchondroma, osteochondroma, chondrosarcoma, myeloma, lymphoma, chordoma and adamantinoma. Our findings show that there is differential SMA expression in primary bone tumours and that identifying the presence or absence of SMA is useful in the differential diagnosis of these lesions. The nature of SMA-expressing cells in bone tumours is uncertain but they are negative for desmin and caldesmon and could represent either myofibroblasts or perivascular cells, such as pericytes.

Biological characterization of preclinical Bioluminescent Osteosarcoma Orthotopic Mouse (BOOM) model: A multi-modality approach

“…Myofibroblasts of the reactive tumor stroma mediate ECM remodeling mainly by active synthesis of extracellular matrix (ECM) components like collagen type I, III, fibronectin, and enzymes like MMPs, urokinase plasminogen activator and fibronectin activation protein [47] , [48] , [49] , [50] . Expression of α-SMA in OS cells as seen in this study and others suggest that (a) highly aggressive OS cells may tend to become de-differentiated and pleomorphic [51] , and (b) tumor cells may fuse with stromal cells such as myofibroblasts from tumor microenvironment [52] . Previous studies suggest that expression of α-SMA in OS tissue may be of prognostic significance [51] , [52] , [53] .…”

A diagnosis of giant cell-rich tumour of bone is supported by p63 immunohistochemistry, when more than 50 % of cells is stained

“…We found high positive predictive value for a diagnosis of GCTB for p63 expression NOS not otherwise specified, BGCRTB benign giant cell-rich tumour of bone, GCRSB giant cell-rich sarcoma of bone SOX 9 by immunohistochemistry [12,13]. Hemingway et al reported the expression of the alpha isoform of smooth actin in a broad range of primary bone tumours, especially in giant cell-rich tumours [14]. They found that alpha smooth actin is strongly and diffusely expressed in mononuclear stromal cells in nonossifying fibroma and brown tumour of hyperparathyroidism.…”

Osteoid osteoma and osteoblastoma: novel histological and immunohistochemical observations as evidence for a single entity

“…In stark contrast to this view, we have demonstrated that the non-osseous element in both osteoid osteoma and osteoblastoma possesses a distinctive immunophenotype; expressing EMA and NSE and lacking SMA expression (ie, refuting a myofibroblastic phenotype). Recently, Hemingway et al 13 also found the stromal cells in osteoid osteoma and osteoblastoma to be negative for SMA by immunohistochemistry. Additionally, we observed the presence of scattered desmin, S100 and PGP9.5 positive, SMA-negative large cells often with degenerate nuclei in both osteoid osteoma and osteoblastoma.…”