Mucocele and Renula

Retention phenomenon

1. Mucocele and renula Dr Amitha

2. The mucocele is a common lesion of the oral mucosa involving salivary glands and their ducts. They result from Traumatic severance of a salivary duct Produced by biting the lips or cheek Pinching the lip by extraction forceps and the like, leading to spillage of mucin into the sorrounding tissues. Such trauma has been implicated in the formation of mucoceles . There is no known history of trauma in many cases. cyst lack epithelial lining they are not true cyst. MUCOCELE

3. Mucoceles are commonly observed in all decades of life , with increased predilection in children and young adults , possibly because of the higher chance of trauma in latter age group. Clinically it appears as a raised , domeshaped vesicles,ranging in size from 1 to 2 mm to several centimetres. There might be a history of rupture, collapse, and refilling which may be repeated. The mucoceles may lie deep in the tissues or exceptionally superficial and thus depending upon the location it present with a bluish , translucent cast, blue color imparted by the spilled mucin below the mucosal surface.

4. Etiology and pathogenesis The mucous retention phenomenon is a common lesion although only few studies have been reported. Many authorities formerly believed that this type of lesion resulted from 1.obstruction of the duct of a minor salivary gland, but experimental investigations on mice by Bhaskar and his associates and rats by Standiush and Shafer failed to produce mucous retention phenomenonby ligation of the submaxillary and sublingual gland ducts. 2. The studies of Bhaskar demonstrated instead that if the salivary duct was severed so that a continuous pooling of of saliva occured in the tissues, a well demarcated cavity developped which was hostologically identical with the natural mucocele.

5. These investigations appear to indicate that traumatic severance of a salivary duct, such as that produced by biting of the lipss or cheek or pinching the lip by extraction forceps, preecedes the development of the retention phenomenon. It is also possible that chronic partial obstruction of the salivary duct , partial obstruction could result from a small piece of intraductal calculus may be the etiologic importance. Occasional cases of calculus in the ducts of accesory salivary glands or sialolithiasis have also been reported. Thus mucocele often have been classifiedas 1.an extra vassaation mucocele 2.a retention mucocele(true retention cyst).

6. HISTOLOGIC FEATURES Mucoceles consist of a cicumscibed cavity in the connective tissue and submucosa producing an obvious elevation of the mucosa with thinning of the epithelium as though it were stretched. The wall of the cavity is made up of lining of compressed fibrous connective tissue and fibroblasts.

7. The connective tissue wall is essentially granulation tissue but in any event it usually shows infiltration by abundant number of polymorphonuclear leukocytes, lymphocytes and plasma cells

8. The lumen of the cyst like cavity is filled with the spilled mucin containing variable numbers of cells,chiefly leukocytes and foamy histiocyes(macrophages). Occasional mucoceles demonstrate an intact flattened epithelial lining. It is probable that this simply represents the portion of the excreatory duct bordering the line of severance, if severance is actually the manner in which these lesion develop. The flattened epithelial lining has been reffered to as epithelium of the “feeder duct” in other instances the epithelium lined mucocele represents a mucous retention cyst.

9. TREATMENT Treatment of the mucous retention phenomenon is excission. If the lesion is simply incised, its contents will be evacuated but rapidly filled as soon as healed. There is occasional recurrence after excision, but this possibility is less likely if the associated salivary gland acini are removed also. The excised tissue should be given for microscopic examination to rule out the possibility of a salivary gland tumor.

10. RANULA The ranula is a form of mucocele which specifically occurs in the floor of the mouth in association with the ducts of the submaxillary and sublingual gland. The etiology and pathogenesis appered to be same as the retention cyst. Some authors believed that it may arise through duct blockage or through the devepment of the ductal aneurysm.

11. Clinical features The lesion which is rare compared to the usual mucocele, develops as a slow enlarging painless mass on side of the floor of the mouth . Since the lesion is usually deep seated one, the overlying mucosa is normal in appearance. If the lesion is superficial the mucosa may have a translucent bluish color.

12. HISTOLOGIC FEATURES The microscopic features are simillar that of smaller mucocele except that a definite epithelial lining is sometimes present. Because of this lining most investigators consider raula as a true retention cyst.

13. PATHOPHYSIOLOGY The development of mucoceles and ranulas depend on the disruption of the flow of saliva from the secretory apparatus of the salivary glands.The lesions are most often associated with mucus extravasation into the adjacent soft tissue caused by a traumatic ductal insult;the insults include a crush type injury and severance of the excreatory duct of the minor salivary gland. The disruption of the secretory glands results in extravassation of the mucous from the gland into the sorrounding soft tissue

14. The rupture of an acinar structure caused by hypertension from the ductal obstruction is another possible mechanism for the development of such lesion. Furthermore, trauma that results in damage to the glandular parenchymal cells in the salivary gland lobules is another potential mechanism. Regarding superficial mucoceles,trauma does not always appear to play important role in the pathogenesis.

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