Cartilaginous Choristoma of the Lower Lip ^†

1. Introduction

The term choristoma applies to cohesive tumor-like mass composed by histologically normal tissue in abnormal locations. Cartilaginous choristomas are a rare finding in the mouth where most frequently arise in the tongue and less commonly in sites such as the buccal mucosa, soft palate and gingiva.

In literature cartilaginous choristomas of the lower lip have been described in 3 women [1].

We report a case of a cartilaginous choristoma occurring in the lower lip in a young man.

2. Material and Methods

A caucasian 37-year-old man referred to our division complaining an asymptomatic and slow-growing lesion at the lower lip. To the patient’s knowledge, the lesion was present since 12 months. There was no reported history of direct trauma or infection in that area before the appearance of the swelling. On examination, there was asymptomatic, mobile submucosal area within the lower lip. Due to the presentation and location, several entities were considered in the differential diagnosis: traumatic fibroma, mucocele, inflamed minor salivary gland, lipoma or a minor salivary gland tumour. In order to obtain the correct diagnostic interpretation, the lesion was then surgically excised.

3. Discussion

The exact cause of a cartilaginous choristoma is unknown. Several theories have been proposed to explain the origin of the cartilage in the soft tissues of oral cavity. However, the embryonic theory and the metaplastic theory are the two main theories favored in the literature. The first theory proposes that the lesions arises from heterotopic fetal cartilaginous remnants.

The metaplastic theory suggests instead that cartilaginous choristomas develop from pluripotent mesenchymal cells either de novo or potentially stimulated by trauma, irritation or chronic inflammation [2].

On gross examination the lesion excised appeared as a nodular formation of 1.3 cm in major dimension, covered by flat and congested mucosa. In section, this formation showed a white-yellowish, focally translucent, surface and soft-elastic consistency.

Microscopically the lesion consisted in a non-capsulated nodule of the sub-epithelial chorion, with well demarcated margins, composed by mature chondroid tissue admixed with fibrous and mature adipose tissue (Figure 1). There was no significant cytological atypia, neither necrosis or evident mitosis. The overlying mucosal layer was uninvolved without significant histological alterations. A mild and scattered lymphoid infiltrate was also associated.

4. Conclusions

This case report depicts a cartilaginous choristoma developed in a rare site.

Unlike the cartilaginous choristomas involving the tongue, where the prevalence is similar among males and females, the lip lesions, albeit reported only in a small number of cases, seems to affect mostly female subjects with a female/male ratio of 3:1.

To our knowledge, this is the first case of a cartilaginous choristoma of the lower lip presenting in a male described in literature.