Oral Focal Mucinosis |
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The normal fibers of the connective
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Quick Review for Patients
| The oral focal mucinosis is a benign localized production of one of the gel or fluid-like substances found between the fibers and cells of connective tissue. Its cause is unknown but a similar lesion occurs on the skin. It is a solitary, soft, nonpainful mass of the oral membrane which remains small but must be removed by conservative surgery because once formed it does not go away. |
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Oral focal mucinosis is the microscopic counterpart of the cutaneous focal mucinosis or cutaneous myxoid cyst. It is not common and its cause is uncertain, but the lesion appears to represent overproduction of hyaluronic acid by local fibroblasts.
Clinical Features
This lesion has a strong female predilection (2 females:1 male) and occurs primarily in young adults. Most maxillofacial cases are seen on bone-bound mucosa. Three fourths of all cases occur on the gingiva and the hard palate is the site for most of the rest. The lesion presents as a sessile, soft, painless nodule with normal surface coloration, sometimes with a somewhat pale appearance (Figure 1). Some cases are lobulated, but surface ulceration is very rare. Lesions are typically less than 2 cm. in greatest dimension.
Pathology and Differential Diagnosis
Oral focal mucinosis consists of a submucosal, well-localized but non-encapsulated nidus of very loose, myxomatous or "mucinous" connective tissue (Figures 2 & 3). More superficial lesions may produce atrophy and loss of rete ridges of the overlying squamous epithelium. Fibroblasts are seen in minimal to moderate numbers within the mucinous area, often demonstrating delicate, fibrillar processes. The mucinous zone is much less vascular than surrounding connective tissues and inflammatory cells are not associated with the lesion except as a perivascular infiltrate of lymphocytic T-cells at the periphery. The hyaluronic acid of the lesion will stain positive with alcian-blue (pH 2.5) in frozen sections, but this is not always the case with paraffin-embedded sections.
Special staining may be necessary in order to differentiate this lesion from other disorders with perivascular infiltrates, such as lupus erythematosus. There are microscopic similarities between oral focal mucinosis and cutaneous mucinosis of infancy, which may represent a localized form of papular mucinosis or lichen myxedematosus.
Differentiation from another look-alike lesion, the oral mucocele, is usually not difficult. The mucocele is more strongly demarcated from surrounding fibrovascular tissues by a peripheral "encapsulation" of granulation tissue, and it has bloated inflammatory cells floating within the extravasated mucus. Mucicarmine staining, of course, will demonstrate mucus in the mucocele.
A slight similarity is also seen between mucinosis and the nerve sheath
myxoma (neurothekeoma, bizarre neurofibroma, pacinian neurofibroma), a variant of
neurofibroma which
rarely affects mucosa of the upper aerodigestive tract. The nerve
sheath myxoma, however, is more circumscribed, has fibrous septa between
multiple myxoid nodules, and has more plump stromal cells.
Treatment and Prognosis
Oral focal mucinosis is treated
by conservative surgical removal. It does not recur with this
treatment.
References (Chronologic Order)
Note: General references can be found by clicking on that topic to the left.
Tomich CE. Oral focal mucinosis: a clinicopathologic and histochemical study of eight cases. Oral Surg Oral Med Oral Pathol 1974; 38:714-724.
Lum D. Cutaneous mucinosis of infancy. Arch Dermatol 1980; 116:198-200.
Buchner A, et al. Oral focal mucinosis. Int J Oral Maxillofac Surg 1990; 19:337-340.
Gnepp DR, Vogler C, Sotelo-Avita C, Kielmovitch IH. Focal mucinosis of the upper aerodigestive tract in children. Human Pathol 1990; 21:856-858.
Stephens CJM, McKee PH, Black MM. The dermal mucinoses: advances in dermatology 1993; 21:293.
Caputo R, Grimalt R, Gelmetti C. Self-healing juvenile cutaneous mucinosis. Arch Dermatol 1995; 131:459-461.
Clark BJ, Mowat A, Fallowfield ME, Lee
FD. Papular mucinosis - is the inflammatory cell infiltrate neoplastic -
the presence of a monotypic plasma cell population demonstrated by in-situ
hybridization. Brit J Dermatol 1996; 135:467-470.
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Figure 3: The normal fibers of the connective tissue are separated by ground substance; fibroblasts are plump and often stellate with thin, wispy dendritic projections. [return to text] |
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