Cellular spindled histiocytic pseudotumor. A lesion previously undescribed in the oral cavity. A diagnostic trap.

Introduction

The cellular spindled histiocytic pseudotumor is a rare, benign, and reactive mass-producing lesion that clinically and histopathologically mimics spindle cell neoplasms. There is only one previous report of twenty cases, all arising in the breast in association with fat necrosis. This is the first description of oral involvement.

Materials and Method

A 70-year-old male presented with a few month history of a painful swelling of the anterior maxilla. Teeth 8 and 9 were extracted approximately three years ago. A CBCT showed a mass partially covered by a thin rim of bone. Clinical suspicion for a neoplastic process was high and an incisional biopsy was submitted for histopathological evaluation.

Results

The lesion consisted of cohesive and compact fascicles of spindle cells with scattered lymphocytes. One focus of necrotic bone and degenerating fat was seen. Two pieces of likely graft foreign material were embedded among lesional cells towards one margin of the submitted tissue. Lesional cells were seen infiltrating surrounding skeletal muscle fibers. Mitotic figures were not obvious. Lesional cells expressed CD68 and CD163 strongly but were negative to AE1/AE3, S100, SMA, desmin, CD34 and CD21. A working diagnosis of reactive proliferation with features like a cellular spindled histiocytic pseudotumor was given. Thorough curettage and follow-up were recommended. Following a thorough curettage, healing was uneventful with no recorded recurrence.

Conclusions

The cellular spindled histiocytic pseudotumor is an exaggerated reactive response to degenerating fat and foreign material. The clinical and histopathological presentation is worrisome for benign and malignant spindle cell tumors. Incisional biopsies may not show degenerating fat or other foreign material. This is the first report of oral involvement. Awareness of this entity will prevent misadventures in its diagnosis and management.