mucoepidermoid carcinoma ( mec ) is the most common type of malignant tumor in the salivary gland and comprises approximately 12% to 23% of malignant tumors in the minor salivary gland1 . the tumor can occur in the minor salivary gland of the lip , buccal mucosa , retromolar region , or tongue and floor of the mouth , but the most frequently involved site is the hard palate2 . mec of the hard palate presents as an asymptomatic , fixed , slow - growing swollen area , sometimes appearing red or blue in color , is fluctuant and ulcerative , and invades the underlying bone3 . mec has diverse biological features and variable clinical symptoms depending on the grade and stage of the tumor4 . low - grade mec is generally slow growing and benign , while high - grade mec is more aggressive , invades the tissue , and metastasizes 4 . treatment of low - grade mec is wide local resection with a tumor - free margin3 . when low - grade mec arises in the hard palate , the tumor is resected along with the involved palate mucosa and any underlying bone5 . a posterior maxillary or hard palate defect bfp has been introduced as a pedicled flap for the closure of oroantral communication7 and has been successfully used to cover oral defects in the posterior maxilla , hard and soft palate , and retromolar region after tooth extraction , saucerization , and tumor resection6 . bfp is located in the masseteric space between the buccinator muscle and the mandibular ramus and masseter muscle and receives a rich blood supply from the superficial temporal , internal maxillary , and facial arteries8 . due to its anatomic location , the bfp can be easily accessed and harvested via an intraoral approach and applied to the posterior oral cavity6 . 4-hexylresorcinol ( 4hr ) is a well - known antiseptic used as an ingredient in mouthwash9 . because the oral cavity is a septic area , 4hr can be used to prevent postoperative infection9 . in addition , 4hr differentiates oral cancer cells by increasing the expression of involucrin and keratin 1010 . if 4hr could accelerate the differentiation of bfp - originated stem cells to the oral epithelium , overall healing time would be reduced . our recent research showed that 4hr ointment suppressed the expression of tumor necrosis factor- ( tnf- ) in burn wounds and increased the epithelialization of skin wounds12 . we present a patient diagnosed with low - grade mec on the left maxillary alveolus and hard palate . the malignant tumor was excised using partial maxillectomy , and the defect was covered with a simple pedicled bfp flap , followed by application of 4hr ointment to heal the wound . a 61-year - old male was referred from a local clinic for continuous swelling of his left maxillary edentulous area after a tooth extraction . he had asymptomatic swelling on the left hard palate and an ulcerative lesion on the left maxillary alveolus.(fig . 1 ) a panoramic view showed generalized bone destruction in the left posterior maxillary area , and incisional biopsy was performed for further evaluation . on histological examination , neoplastic proliferation of the epithelial cells , which contained mucous cells , was observed . magnetic resonance imaging ( mri ) was performed , and the mass was observed with central necrosis in the left hard palate.(fig . a ) the mass had destroyed the alveolar process of the maxilla and extended into the soft palate , left maxillary sinus , and inferior wall of the left nasal cavity.(fig . b ) multiple nodularshaped lymph nodes were observed around the submandibular gland on contrast - enhanced computed tomography ( ct ) . metastasis of the lymph nodes was suspected in the submental , submandibular , and upper jugular areas based on positron emission tomography ( pet ) ct ( pet - ct ) . under general anesthesia , a partial maxillectomy was performed from the left maxilla canine to the posterior maxillary tuberosity . 3 ) an elective neck dissection was performed to remove the left submental , submandibular , and upper jugular lymph nodes . 4 ) upon histological examination , mucin - producing cells mixed with epithelioid tumor cells were evident in the main tumor mass . a small microcystic formation was also observed . we applied 4hr ointment on the bfp - grafted area 1 day after surgery to promote re - epithelialization . re - epithelialization of the grafted bfp was observed 20 days after surgery ( fig . a ) , and the defect was completely covered without any complication 8 weeks after surgery.(fig . b ) mri showed that the bfp was located in the left maxillary alveolus and hard palate defect.(fig . 6 ) evidence of recurrence and distant metastasis were not observed on pet - ct at the 5-month follow - up visit . mecs are classified into low , intermediate , and high grades depending on the relative portion of cell types4 . mec is composed of various types of cells including mucous - producing , squamous , and intermediate1 . low - grade mec has abundant mucous - producing cells , cystic structures , and few squamous cells3 . intermediate - grade mec is histologically between low - grade and high - grade mec and has fewer cysts and more prominent intermediate cells with a minor degree of mitotic activity and cellular atypia1 . high - grade mec has a relatively high proportion of squamous cells , a greater degree of mitotic activity , and infrequent mucous - producing cells or cysts1 . high - grade mec has local infiltration and grows aggressively , similar to squamous cell carcinoma4 . radiologically , high - grade mec has irregular , poorly - defined margins and infiltrative adjacent tissue , while low - grade mec demonstrates a well - delineated mass similar to a benign tumor3 . the mec treatment varies based on the tumor location , clinical stage , and histological grade3 . if mec occurs in the parotid gland , a parotidectomy is performed , and the facial nerve will be excised413 . mec of the minor salivary gland in the hard palate is treated with wide local resection3 . low - grade mec is surgically excised in a single piece along with the involved underlying mucosa and bone for an adequate tumor - free margin5 . high - grade mec has local infiltration and regional lymph node metastasis1415 , requiring wider surgical resection with postoperative radiotherapy or chemotherapy116 . the biopsy result of the present case was low - grade mec , and a reactive lymph node was suspected around the left submandibular gland based on contrast ct . low - grade mec has a favorable prognosis ; the 5-year survival rate is 76% to 95% , and recurrence has rarely been reported17 . the bfp has been widely used as a pedicled flap in the oral cavity for closure of an oroantral fistula , coverage of a sequestrectomy defect in osteomyelitis , regenerative treatment of peri - implantitis , and treatment of oral submucous fibrosis68 . reconstruction using the bfp is considered a reliable technique due to an excellent blood supply , minimal morbidity , easy harvest , and simplicity18 . the posterior maxilla , hard palate , and retromolar trigone are the ideal defects for reconstruction with the bfp due to anatomical proximity to these areas6 . the bfp provides a 743 cm pedicled tissue when proper dissection and advancement are performed11 . 3 ) the involved defect area was the left maxillary canine to the tuberosity , the hard palate , and the sinus mucosa floor . we carefully harvested and advanced the bfp flap and successfully covered the defect without tension.(fig . 4 ) epithelization of the grafted bfp begins 1 week after surgery , and complete healing is noted within 4 to 6 weeks6 . this is accomplished by migration of the epithelial cells from the surrounding tissue in the flap margin19 . at first , the superficial layer of the bfp is replaced with granulation tissue ; however , this eventually turns into stratified squamous epithelium18 . histologically , parakeratotic squamous epithelium covers the healed site , and dense fibrous connective tissue is present in the subcutaneous stroma18 . to promote re - epithelialization of the large graft area , we applied 4hr ointment on the bfp area due to its antiseptic and broad - spectrum antibacterial properties10 . 4hr inhibits foreign body giant cell formation via the diacylglycerol kinase ( dagk)-mediated pathway20 and suppresses the expression of tnf-12 . in a recent study , 4hr ointment was applied to a burn wound , and rapid epithelialization and collagen regeneration occurred12 . in the present study a ) during the healing process , minimal complications such as infection , hematoma , or partial necrosis were noted11 . however , these complications have rarely been reported , and as in our previous study , most cases of bfp flap successfully covered the saucerization defect without any complications14 . in the present case , the grafted bfp was completely epithelialized and covered the defect.(fig . b ) the hard palate is a frequently involved site of low - grade mec14 . we surgically resected low - grade mec on the left maxillary alveolus and hard palate and successfully covered the large defect with a bfp flap . 4hr ointment was applied to the fat graft area for rapid re - epithelialization and wound healing . based on the results from this case , we confirmed that bfp grafting is a simple , reliable , and minimally complicated technique for reconstruction of posterior palatal defects , and 4hr is a clinically useful ingredient to promote re - epithelialization of fat .
mucoepidermoid carcinoma ( mec ) is the most common type of malignant neoplasm in the minor salivary gland . 
 the hard palate is a frequently involved site of mec . 
 the treatment of low - grade mec on the hard palate is wide local resection with a tumor - free margin . in the present case , 
 the maxillary defect was reconstructed using a buccal fat pad ( bfp ) flap , followed by application of 4-hexylresorcinol ( 4hr ) ointment for 2 weeks . 
 the grafted bfp successfully covered the tumor resection defect without tension and demonstrated complete re - epithelialization without any complications .