Lymphomatoid granulomatosis (LYG) is an uncommon Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disorder distinct from lymphoma. LYG primarily occurs in the lung with or without accompanied lesions in the skin, central nervous system, kidney, gastrointestinal tract, nose, eyes, liver and oral cavity. Solitary extrapulmonary LYG is extremely rare, and whether solitary lesions progress onto pulmonary development and dysfunction is controversial. Herein, we report a case on a solitary LYG in the maxilla gingiva with bone exposure in a patient who had been taking methotrexate for rheumatoid arthritis.

Juvenile xanthogranuloma (JXG) is a benign histiocytosis that occurs in the pediatric population. Cutaneous JXG is the most common form, while extracutaneous lesions, including oral JXG, is extremely rare. Cutaneous JXG can occur as multiple lesions and may have systemic visceral involvement, but this is not seen in oral JXG. In this case, we report a solitary oral JXG at the gingiva in a 3-year old male.

Small cell osteosarcoma of bone, which was first described in 1979, is an unusual variant of osteosarcoma. Osteoid production by tumor cells is frequently focal or minimal, making the differential diagnosis with other small round cell tumors of bone difficult. Here, we present a rare case of small cell osteosarcoma of the mandible appearing as bony bulging mass in 31-year-old male who has neither tenderness nor paresthesia. Histologically, the tumor contains hypercellular cartilage and abnormal osteoid associated with small round to ovoid malignant cells. Awareness of small cell osteosarcoma should be emphasized because it has worse prognosis than both other small round cell tumor and conventional osteosarcoma.

Nodular fasciitis is defined by the World Health Organization as a benign proliferative fibroblastic lesion. It was first described in 1955 by Konwaler et al. and also known as “nodular pseudosarcomatous fasciitis” and “infiltrative fasciitis”, which reflect the lesion’s rapid growth, dense cellularity, alarming mitotoic activity and lack of circumscription. Here, we report a case of nodular fasciitis, which appeared as subcutaneous mass of right perizygoma area in 40-year-old Korean female. She had no history of trauma or cosmetic surgery related with the lesion. She disclosed that the mass grew rapidly for last 2 months. Computed tomography showed relatively well-defined spherical mass with 1.2 cm in diameter. Under local anesthesia the mass was resected by intraoral approach. The histological examination revealed a relatively poor-dermacated mass with high cellularity, which was composed with infiltrative spindle-shaped cells without accompanying inflammatory reactions. The tumor cells were partially positive for α-smooth muscle actin and β-catenin, but negative for cytokeratin AE1/3, S-100, desmin, and CD34. Therefore, the lesion was pathologically diagnosed as nodular fasciitis. Although nodular fasciitis is known to pseudosarcomatous benign reactive lesion, the clinician need to follow up the patient periodically. The reasons are as follows; Nodular fasciitis may accompany nuclear accumulation of β-catenin, which imply neoplastic process rather than reactive process of the lesion. Moreover, it has many histological similarities with inflammatory myofibroblastic tumor which have malignant transformation tendency. Further research for mesenchymal tumor could help our understanding for the disease entity of nodular fasciitis

Angiosarcoma is an extremely rare sarcoma arising from oral mucosa. We report a case of angiosarcoma in the right maxillary gingiva causing excessive bleeding. The lesion exhibited typical histologic features of angiosarcoma, showing infiltrative proliferation of polygonal endothelial cells and arborizing blood vessels. Tumor cells showed expression of CD 31 and factor VIII, but no expression of CD 34 antigen. The patient expired due to severe bleeding in the oral cavity.