Undifferentiated malignant neoplasm involving the interdental gingiva: a case report.

BACKGROUND Metastases to the gingiva are uncommon. They can be a diagnostic challenge clinically because of their rarity and tendency to mimic benign lesions. In this report, we present a case of an undifferentiated malignant neoplasm of unknown origin presenting as benign inflammatory gingival lesions and we review the literature on metastases to the gingiva. METHODS A 44-year-old female patient was referred by a local periodontist for evaluation of multiple painless gingival lesions that clinically resembled pyogenic granulomas or periodontal abscesses, but with an uncharacteristic multifocal presentation in the background of good oral hygiene. Her medical history was unremarkable except for recent weight loss. Periapical radiographs were obtained, as well as two incisional biopsies, one placed in formalin for routine histology and immunohistochemistry, the other in phosphate buffered saline for flow cytometry. RESULTS Radiographic findings were non-contributory for hard tissue pathoses. Histopathological findings were consistent with a poorly differentiated malignancy, suggestive of metastatic disease. Immunohistochemical studies and flow cytometry were unsupportive in delineating any tumor differentiation. The patient subsequently developed multiple tumors throughout the body with similar histopathological findings, yet no primary tumor was identified and a definitive diagnosis could not be rendered. She was discharged one month later in poor condition with the principal diagnosis of hemorrhage/ pancytopenia, and a secondary diagnosis of metastatic head and neck cancer. CONCLUSION This case of malignant metastatic tumor of unknown origin presenting as benign gingival lesions illustrates the importance of thorough patient evaluation, which should include a biopsy when necessary for definitive diagnosis.