Morphological and immunohistochemical features can potentially help with the differential diagnosis of rare oral mesenchymal tumors

Objective

The aim of this study was to evaluate the features of rare oral and maxillofacial benign and malignant tumors of fibroblastic, myofibroblastic and fibrohistiocytic origin in an attempt to contribute to the diagnosis of these tumors.

Methods

The sample consisted of 16 cases of benign fibrohistiocytic (BFH) tumor, myofibroma (MF), solitary fibrous tumor (SFT), fibrosarcoma (FS), dermatofibrosarcoma protuberans (DFSP), and myofibroblastic sarcoma (MFS), obtained from a laboratory of oral pathology. They were submitted to morphological, histochemical (Masson’s trichrome), and immunohistochemical (α-SMA, vimentin, desmin, CD34, Bcl-2, S100, CD68, CD99, and Ki-67) analysis.

Results

Morphological analysis revealed variable features in the tumors studied. Masson’s trichrome resulted in blue staining in most cases. Regarding the immunohistochemical features, all cases were positive for vimentin and negative for desmin. The BFH tumors exhibited positive staining for CD68 and S100, while MFs were positive for α-SMA and SFTs were positive for CD34, CD99 and Bcl-2. With respect to malignant tumors, DFSP was positive for CD34 and Bcl-2 and MFS was positive for α-SMA and Bcl-2, while FS was negative for most of the antibodies analyzed. A higher proliferation index (Ki-67) was observed in malignant tumors.

Conclusions

Considering their similarity, the use of auxiliary techniques might help in the differential diagnosis of these tumors.