Rare case of giant myoepithelioma in minor salivary glands of palate in a 9-year-old child

Abstract

Myoepitheliomas (MEs) are extremely rare benign neoplasms composed of ectodermally derived contractile smooth muscle cells (myoepithelial cells). Various tissues such as the salivary glands, breast, larynx, and sweat glands show the presence of these myoepithelial cells. They occur, principally, in the parotid gland and infrequently in minor salivary glands. The term “Myoepitheliomas” was first coined by Sheldon in 1943. It is an uncommon salivary gland tumor which accounts for < 1% of all major and minor salivary gland tumors. Batasakis considers the ME to be “one-sided” variant at the opposite end of the spectrum from the pleomorphic adenoma. There are distinct histological and immunohistochemical characteristics of the tumor which aid in the diagnosis. ME of the palate is uncommon, and only a limited number of cases have been reported in the English literature. It shows a benign clinical course with recurrence in up to 20% of cases without metastasis. The present article sheds light on the presence of ME of minor salivary glands in the palate of 9-year-old child.

Myoepithelioma of parotid gland: a case report

“…Many of these differential diagnoses share clinical and radiological features with each other so biopsy is essential for diagnostic confirmation. 4 The recurrence rate of ME is described as 15-18%, with possible malignant transformation associated to long term cases or recurrences, which has been attributed to the overexpression of c kit receptors and mutation of the gene p-53. 1,2,10 Thus, even after complete excision of the lesion, follow-up of these patients for an extended period of time is recommended.…”

“…1,2 ME arises predominantly from major and minor SG, affecting parotid gland in 50% of cases, sublingual gland in 33% of the cases and submandibular gland in 13%. [3][4][5] The term ME emerged in 1943 to describe a group of tumors histologically composed of solitary myoepithelial cells, initially described as a variant of pleomorphic adenoma. In 1991, the world health organization classified the ME as a distinct entity.…”

“…In cases of malignant ME, myoepithelial carcinoma, the cells present with cellular atypia, cellular pleomorphism, cell necrosis, increased mitotic figures, invasive growth pattern or a combination of these and are clinically characterized by a more aggressive behavior and a higher recurrence rate. 1,4,6 Although ME can appear at any age, with cases described between 8 and 35 years old, the usual age of presentation is between the 3 rd and 5 th decades of life. 1,4 It typically presents as painless mass, with slowly progressive growth and which, depending on its location, can cause different types of symptoms usually related to obstruction caused, mostly at advanced stage.…”

“…1,4,6 Although ME can appear at any age, with cases described between 8 and 35 years old, the usual age of presentation is between the 3 rd and 5 th decades of life. 1,4 It typically presents as painless mass, with slowly progressive growth and which, depending on its location, can cause different types of symptoms usually related to obstruction caused, mostly at advanced stage. Prognosis is usually favorable and recurrence is rare after complete excision.…”

“…Prognosis is usually favorable and recurrence is rare after complete excision. 4,6 Although the rate of malignancy is very low, metastases can arise from apparently benign lesions and recurrence should be considered as potentially unrecognized malignancy. 1,4 A rare case of ME of the parotid gland is presented below, with a discussion of its imaging and histological characteristics and treatment implemented.…”