History of Present Illness
The patient had the chief complaint of a loose crown on the maxillary right central incisor, which had been recemented three times previously. The crowns had been placed on the right and left central incisors 26 years previously. During the examination a lump was observed in the upper lip which the patient reported had been present for about 6 years. She said it did not bother her, and she felt that it did not alter her facial appearance. She did not remember any trauma to the area that coincided with the development of this lip swelling.
The patient reported a history of environmental allergies and sinus congestion for which she took medication. She had a physical examination with adjunctive laboratory studies approximately one year ago, and she stated the results of this medical evaluation were satisfactory.
There was a gray-black discoloration of the alveolar mucosa overlying the apex of the maxillary left central incisor. (Figure 1) External clinical examination revealed subtle fullness of the left upper lip. (Figure 2) Intraoral examination showed erythema of the labial marginal gingiva adjacent to the right maxillary central incisor. In addition, there was firmness to the left upper lip. The skin and mucosal surfaces overlying the enlargement were normal in appearance. The firm, fixed, and nontender lip mass measured 1.5 x 1.2 x 0.7cm.
Figure 1. Gray-black pigmentation in the apical area of the left central incisor and a firm, non-movable mass in the upper lip.
Figure 2. Subtle fullness just to the left of the midline of the left upper lip.
A periapical radiograph was taken of the maxillary incisor region, which revealed previous endodontic therapy of the central and left lateral incisors and an apical retrofill procedure of the left central incisor. (Figure 3) In addition, a radiograph was taken of the soft tissue of the left upper lip to determine if there was evidence of entrapped amalgam or other foreign material. (Figure 4)
Figure 3. Periapical radiograph showing root canal therapy and retrofill with amalgam debris in the periapical area.
Figure 4. Soft tissue radiograph of the upper lip showing no evidence of amalgam particles or other foreign material.
Incisional Biopsy and Photomicrographs
An excisional biopsy was attempted of the upper lip mass. Microscopic examination revealed minor salivary gland tissue, fibrous connective tissue, muscle, nerve, and blood vessels. Throughout the specimen were lobulated, rounded islands and cords of isomorphic cells with scant cytoplasm and dark blue nuclei. (Figure 5) Within the islands of darkly staining cells were prominent “cystic” spaces filled with pale blue, homogenous, and acellular material. These islands and cords of cells infiltrated through the salivary gland tissue, muscle, and fibrous connective tissue. The infiltrating islands of cells extended to the margins of the surgical specimen. In areas, perineural invasion by the tumor cells was identified. (Figure 6)
Figure 5. Islands of cells with “cystic” spaces filled with light blue acellular material. The islands are infiltrating the normal salivary gland tissue.
Figure 6. Islands of tumor cells in close approximation to a moderate-sized nerve