Primary gingival leiomyosarcoma. A clinicopathological study of 1 case with prolonged survival

Leiomyosarcoma is a relatively uncommon mesenchymal tumor that exhibits smooth-muscle differentiation. Only 3 to 10% of leiomyosarcomas arise in the head and neck, the nose and paranasal sinuses, skin and subcutaneous tissue and cervical esophagus being the most common localizations. Most leiomyosarcomas involving the oral tissues primarily affect the maxillary sinus, the maxillary or mandibular bone. A review of the English-language literature since 1908 revealed 30 reported cases of primary leiomyosarcoma of the oral mucosa and soft tissues.

We report on a case of gingival leiomyosarcoma, arising in a 31-year-old female and involving the upper alveolar mucosa. Following the diagnosis of malignant neoplasm on frozen sections and an en-block resection, the tumour was formalin-fixed and paraffin embedded for histological and immunohistochemical examination.

Microscopically, the tumor was composed of interlacing fascicles of spindle-shaped cells with elongated, blunt-ended nuclei and eosinophilic cytoplasm, containing PAS-positive granules. Mitoses, both typical and atypical, and scattered necrotic foci were present. Consistent desmin, muscle specific and alpha-smooth muscle-specific, and vimentin immunoreactivity was demonstrated in the tumor cells. The patient is alive and free of disease at a 7-year follow-up.

Intra-oral leiomyosarcomas are exceptionally rare. Accurate diagnosis and treatment is largely based on the careful search of clinical signs indicative of malignancy (e.g., neoplastic bone destruction, wide invasion of adjacent tissues) and intra-operative (frozen sections) examination of the lesion. Though the case reported herein showed an attenuated clinical behavior, prolonged follow-up is mandatory in view of possible tumor relapse.