A novel mucocele: Myxoglobulosis.

Oral extravasation mucoceles are among the most widely recognized submucosal lesions which are usually a result of trauma involving salivary glands and their ducts. This paper reports a case of a 40-year-old female patient with a chief complaint of a painless swelling on the lower lip since 6 months. Upon a provisional diagnosis of mucocele, surgical excision was carried out. Histopathological examination revealed a mucus extravasation cyst having lumen filled with unique mucinous globular structures similar to a rare variant of appendiceal mucocele, myxoglobulosis. Copyright:

INTRODUCTION

Mucoceles are one of the most common benign soft tissue lesions of the oral cavity which often results due to local trauma and consequent rupture of salivary gland ducts, especially in the lower lip.[1] They represent a localized accumulation of saliva that is classified into two types based on its pathogenesis. The term mucus extravasation phenomenon is used when there is mucin leakage into the connective tissue from a severed minor salivary duct. Whereas, mucus retention cyst is accumulation of mucin within the lumen of a distally obstructed salivary duct.[2] Apart from the conventional classification, other variants are also seen: (1) superficial mucoceles, (2) mucoceles with myxoglobulosis and (3) mucoceles exhibiting papillary synovial metaplasia like change.[3] The case reported in this article, reveals an extravasation mucocele showing unique globular organization of mucous content representing myxoglobulosis.

CASE REPORT

A 40-year-old female patient was referred for evaluation of an asymptomatic swelling on the lower lip of 6 months duration with a history of local trauma. Clinical examination revealed a well-defined, nontender, smooth-surfaced, roughly oval, fluctuant swelling [Figure 1]. No relevant medical history was elicited. Oral hygiene was fair. A provisional diagnosis of mucocele was made; the lesion was excised under local anesthesia. Histopathological examination of the excised tissue revealed cystic lumen devoid of lining epithelium and surrounded by compressed granulation tissue and peripherally located mixed salivary glands. The lumen was filled with numerous mucinous globular structures which were oval or round in shape and of varying sizes [Figure 2]. Most of the globules present in the cystic lumen were attached to the surrounding cystic capsule and seemed dissociated from one another because of their globular organization. Some of the globules were suspended freely within the lumen [Figure 3]. Individual globules exhibited a mildly cellular core with peripheral laminations of dystrophic calcifications [Figure 4]. The granulation tissue forming the cystic wall was highly cellular, consisting of chronic inflammatory cells. The mucinous globules showed positive results for PAS and Alcian blue [Figures 3 and 4].

Figure 1

Clinical image shows a well-defined, roughly oval swelling on the lower lip

Figure 2

Histopathological image shows presence of large, eosinophilic globules having lamellated or whorled appearance (H&E stain, ×4)

Figure 3

Histopathological image shows abundant mucin within the globules attached to the surrounding cystic capsule and few globules suspended freely within the lumen (PAS stain, ×4)

Figure 4

Histopathological image shows presence of mucin in the periphery with central cellular core (Alcian blue stain, ×10)

DISCUSSION

Mucus extravasation phenomenon most commonly affects children or young adults, aged between 10 and 30 years. About 80%–90% cases are observed in the lower lip as an asymptomatic swelling with translucent or bluish hue.[2] Histologically, the presence of a well-demarcated interstitial mucin surrounded by a granulation tissue containing neutrophils and multinucleated giant cells in the submucosa serves as a peculiar feature to diagnose mucus extravasation phenomenon.[2] Myxoglobulosis or caviar appendix is a variant of mucocele characterized by the presence of opaque pearl-like globules composed of mucoid material. They are generally 2–3 mm in diameter and form clusters that appear like “fish eggs” or frogspawns.” The first case of myxoglobulosis was accidentally discovered during a postmortem examination by Latham in the year 1897.[4]

In the present case, overall clinical and histopathological features were suggestive of an extravasation mucocele. Albeit, the diagnosis of extravasation mucocele is usually straightforward, the presence of globular structures within the lumen is unique and this condition is referred to as myxoglobulosis. The globules present in this case showed mildly cellular core with peripheral laminations of dystrophic calcifications. This might be a result of a long-standing lesion which has become less cellular over a period of time as stated by KA Shah.[5]

The precise etiology and pathogenesis of myxoglobulosis remain unknown. However, the etiological factors for myxoglobulosis of the intestine or appendix, as suggested by Probstein and Lassar include bacteria and necrotic epithelial debris which represent the focus of infection for mucin pooling.[4] An uncommon histologic feature was observed in the lower lip mucocele which bore a resemblance to globules observed in a variant of mucocele of the vermiform appendix by Li et al. in 1997 and thus was described as “myxoglobulosis.” The globules represent an attempt to organize the mucin by the granulation tissue capsule, which is then expelled into the lumen because of persistent mechanical stresses.[6] Ide and Kusama proposed that the formation of these pearl-like globules of salivary mucocele develop as a result of a rich reparative interaction of the capsular granulation tissue in response to the intraluminal pooling of mucin.[6] Despite the etiology, the significance of myxoglobulosis is exclusively academic. Mucus extravasation phenomenon associated with myxoglobulosis does not reveal distinguishing clinical features, nor is the prognosis any different from conventional types. Treatment includes excision of salivary gland and associated duct along with the pool of extravasated mucin to avoid recurrence. Regardless of not being clinically significant, myxoglobulosis continues to be a remarkable phenomenon for its relative rarity.[2]

Declaration of patient consent

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Conflicts of interest

There are no conflicts of interest.