Oral focal mucinosis: case report

SUMMARY

Oral focal mucinosis (OFM) is an uncommon disease of unknown aetiology. It is considered to be the oral counterpart of cutaneous focal mucinosis and cutaneous myxoid cyst and it is characterized by a focal myxoid degeneration of the connective tissue. A preoperative diagnosis is almost impossible, and the clinical suspicion, usually made by exclusion, must be confirmed by a bioptic examination followed by histological observations.

The Authors report a case of focal oral mucinosis diagnosed and treated in a male adult patient.

Introduction

Oral focal mucinosis (OFM) is a rare disease that affects different localised areas of the mouth, where the connective tissue undergoes a focal degeneration. It has been described for the first time by Tomich in 1973 (1) and only few cases have been described in literature (2, 6), two of them observed on tongue (7). It is considered to be the oral expression of the focal skin mucinosis and myxoid skin cysts, thus presenting specific histological features (8). Focal skin mucinosis can be seen as a lesion of mesenchymal origin in which fibroblasts predominate. In oral focal mucinosis there is a hyaluronic acid overproduction by fibroblasts that reduce the production of collagen, elastic fibers, almost absent, and collagen fibers that disgregate and are replaced by varying amounts of mucin. Skin onsets seem not to be associated with oral lesions.

The diagnosis of OFM is usually made by exclusion: an area of similar myxoid tissue is found in the inflammatory fibroepithelial hyperplasia, lesion objectively characterized by inflammation and fibrosis (9). Differential diagnosis can be made with mixoma, that is expressed as an oral soft tissues lesion with compromise of the underlying bone, showing well circumscribed and distinguishable from surrounding tissue. OFM appears with rather blurred margins confusing with tissues that surround it, without damaging adjacent anatomical structures. Most of inflammatory lesions, such as gingivitis, fibrous hyperplasia, epulis, pyogenic granuloma or tumors, such as peripheral fibroma and ossifying fibroma, and non-plaque associated lesions manifesting as a swelling gum, as mucocele, create differential diagnosis problems with focal oral mucinosis (10). In any case, to confirm the clinical suspicion a bioptic examination followed by histological observations is needed.

OFM frequently affects women in a wide range of age, localizing in 80% of cases at the gum, generally in the jaw, and secondly in the palatal region, on the lips or tongue.

It clinically presents as a swelling that does not exceed 2 cm in diameter, sessile of firm consistency, that mimics in the surrounding mucosa for colour, and is generally asymptomatic.

The aetiology remains still now unknown. Surgical treatment is the unique therapy. OFM generally does not tend to give relapse.

Case report

A 35 years old male patient, non-smoker, with good oral hygiene and a swelling localized in the vestibular attached gingiva of the upper right central incisive (Figs. 1, 2) came to our observation. His medical and dental history was non-contributory. The rounded of about 10 mm in diameter lesion was sessile, with hard consistency, adherent to the underlying tissues and pinkish in colour. Surgery excisional biopsy was scheduled. Prior local anesthesia with 2% mepivacaine and vasoconstrictor 1:1.000.000, a partial thickness circular excision of the swelling, that presented bluish-grey in colour, was performed (Fig. 3). Macroscopic examination of the lesion did not give any indications for a diagnosis. Healing was asymptomatic and without recurrence at 6 months from surgery. Histological examination diagnosed a oral focal mucinosis (11).

Figure 1.

Intra-oral aspect of patient’s mouth. An elevated mass can be observed located on the gingiva of the right upper central incisor.

Figure 2.

Intra-oral particular of the gingival rounded lesion. At the clinical examination it appears to be sessile, with hard consistency, adherent to the underlying tissues and pinkish in colour. The lesion measured about 10 mm in diameter.

Figure 3.

The site immediately after surgical excisional biopsy of the lesion.

At histological examination the lesion appeared to be as a myxoid tissue (Pas Alcian+) in which fusiform or stellate fibroblasts were immersed. The absence of flogosis and fibrosis excluded the inflammatory fibroepithelial hyperplasia (Figs. 4, 5) and permitted the diagnosis of oral focal mucinosis.

Figure 4.

Histological examination of the lesion: paraffin section. The lesion appeared to be as a myxoid tissue (Pas Alcian +) in which fusiform or stellate fibroblasts were immersed 200X.

Figure 5.

Histological examination of the lesion: 500X.