Introduction
Myxoglobulosis, a variant of mucocele, was first coined by Von Hansemann in 1914.1 Mucoceles of the oral cavity occurs due to local trauma or rupture of the salivary gland ducts in lower lip.2 Localized accumulation of mucus can present in different forms based on the pathogenesis. Severed salivary duct causing leakage of mucin into the extracellular tissue is called as Mucus extravasation phenomenon. When a salivary duct is obstructed and causes accumulation of mucin in the lumen, it leads to the formation of mucus retention cyst.3
Apart from these forms, mucoceles can present as different variants such as superficial mucoceles, mucoceles with myxoglobulosis, mucoceles with papillary synovial metaplasia like change.4 these multiple small intraluminal globules were previously termed as “frog eggs” or “fish eggs” appearance and constitute as a special type of mucocele.5
Myxoglobulosis are eosinophilic, amorphous, lamellar, fibrillary material seen as a globular structure without epithelium.6 These globules are present either inside the lumen or in the mucin extravasted area in the connective tissue.4, 7 Mucoceles with myxoglobulosis can occur in many organs such as the oral cavity, appendix, lacrimal sac,paranasal sinuses,urinary bladder.7
This case report depicts an uncommon variant of mucocele with myxoglobulosis presenting as an asymptomatic swelling over the lower lip.
Case Report
A 17 years old male patient visited the hospital with the complaints of painless swelling over lower lip for past 2 months. Examination revealed a single, dome shaped. bluish, painless, fluid filled cystic lesion measuring about 2x2cm over the left side of the lower lip, overlying mucosa was intact, no ulceration seen. Swelling was soft in consistency, mobile, and well-defined. Clinically, it was diagnosed to be a case of mucus retention cyst or mucocele of lower lip. Gross examination revealed fluid filled single cyst measuring about 2x2x1.5cm, soft in consistency with smooth outer surface.
Figure 1
Histopathological picture shows the presence of myxoglobules which are surrounded by dense mixed inflammatory cell infiltrates..(H&E, 10X)
Figure 2
Myxoglobules which are peripherally cellular and centrally acellular and hyalinised.(H&E,40x)
Figure 3
Histopathological picture shows lobules of mucinous glands surrounded by dense inflammatory cell infiltrate.(H&E, 10X)
Cyst was excised and sent for histopathological examination. H&E-stained slides show stratified squamous epithelium with subepithelial region showing a cystic cavity lined by columnar lining enclosing abundant mucin and mucinophages. Cystic cavity also shows the presence of eosinophilic, acellular globules with concentric hyalinized mucinous material depicting myxoglobulous structures (Figure 1, Figure 2 ). Adjacent stroma shows presence of lobules of mucinous glands (Figure 3 ), fibrous stroma with dense inflammation and congested blood vessels.
With all these histopathological findings this case was diagnosed as Mucocele with myxoglobulosis in the lower lip.
Discussion
Mucoceles are the most frequent non-neoplastic lesions of the oral cavity, most commonly affects the minor salivary glands . Li et al in 1997 was first to observe globular intraluminal organisation of mucus content in a case of mucocele removed from 10-year-old child. During those times myxoglobulosis was reported only in appendiceal mucoceles 8. But now myxoglobulosis was found in oral cavity, lacrimal sac, larynx, appendix, bladder and paranasal sinuses 7. Even though the presence of myxoglobulosis is found in all these sites, its aetiology and pathogenesis remain unclear 1.
Shah et al 6 states that when there is an extrusion of the mucin into the surrounding tissue, collagen fibres get separated. The dissociated collagen fibres will be surrounded by neutrophils and macrophages which results in enzymatic breakdown. The collagen fibres surrounded by the inflammatory cells form a globular architecture forming myxoglobulosis.
Various hypotheses states that a core or nidus for mucin deposition is needed to initiate the formation of globules 9. Few authors have reported that from necrotic epithelium or bacterial debris, the small mucinous masses can develop into dilated glandular crypts forming myxoglobules 10, 11. Popularly known and accepted hypothesis of Lubin and Berle stated that each globule is nothing but the necrotic fragment of the granulation tissue. 12
Ide and Kusama reported that these globules of salivary mucocele develop due to the rich reparative interaction of the capsular granulation tissue in response to the intraluminal pooling of mucin. 13
Other than myxoglobulosis, oral mucocele can show papillary synovial metaplasia and clear cell changes. Due to replacement of granulation tissue by folded membranes with villi, mucoceles undergo papillary synovial metaplasia and clear cell changes. Marked reduction in the cystic cavity due to the presence of broad papillae projecting into the lumen causing collapsed lumen. 7
Pina et al reported a case of oral mucocele, which consists of purely macrophages with extensive clear vacuolated cytoplasm forming signet ring alterations. 12
The diagnosis of myxoglobulosis can be done only radiological and pathological evaluation. In cases of appendiceal myxoglobulosis, CT scans suggest the presence of mucinous globules, but needs pathological examination for confirmation. 13
The major differential for myxoglobulosis is collagenous spherulosis.Collagenous spherulosis is frequently seen in all salivary gland tumours, Schwannomas, Chondroid syringoms, proliferative lesions of breast. Collagenous spherulosis are considered to be myoepithelial in origin ,acellular and are positive for collagen,p63 and negative for mucin stains. 14
Mucocele with myxoglobulosis does not have any distinguishing clinical feature. Even the prognosis is same as the conventional mucocele. 10
Treatment includes excision of the salivary gland along with the lesion to avoid recurrence. 15
Conclusion
Oral mucoceles presents with so many histological variations. Etiopathogenesis of these changes still remains unclear. 4 These lesions don’t carry any significant finding clinically mimics the conventional mucoceles. However, these variations can be more prominent in some cases causing diagnostic difficulties. Hence it is considered to be important to know about the histopathological variants in oral mucoceles.
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