LMs are benign connective tissue tumors involving the smooth muscle components of the organs. They occur mostly in the uterus, small intestine and esophagus. In contrast, LMs occur rarely in the head and neck region due to the paucity of smooth muscle [1]. Three different types of leiomyoma are recognized: the common leiomyoma, the vascular leiomyoma (angiomyoma) and the epithelioid leiomyoma. Although the smooth muscle were rarely seen in laryngeal tissues, all three types have been found in the larynx [2]. Histopathologically, angiomyoma is made up of many variant blood vessels. Whirlpools of smooth muscle fibers can be observed around the vascular endothelium, but lacking mitotic and well-differentiated smooth muscle bundles, and sometimes accompanied by mucoid lesions[3]. Epithelioid leiomyomas manifest as tumor cell masses with round or oval nucleus, with or without vacuoles, and clear cell changes in the rich eosinophilic cytoplasm [4]. The common leiomyoma are characterized by intertwined spindle cells, cigar-shaped nuclei, eosinophilic cytoplasm, and a positive reaction to smooth-muscle actin or desmin[1]. The case we reported here is consistent with the pathological diagnosis of common leiomyomas. LMs that occur in the larynx are extremely rare. We searched the PubMed and Geenmedical databases using laryngeal leiomyoma as a keyword and analyzed the search results (Table 1). To our knowledge, including this case, there are only 12 literatures reported relevant patients. Among them, there were 12 men and 5 women between 7 and 75 years old, half of which were between 40 and 70 years old and the median was 48 years old. Apparently, a male dominance (11/16) was observed as shown in Table 1. LMs that occur in the upper aerodigestive tract can be distributed in the nose, pharynx, and trachea. The most commonly reported sites of laryngeal LMs were the supraglottic area (7/16), the glottal area (5/16) and the subglottic area (4/16) in order. The common symptoms of LMs in the glottic region were hoarseness. Most subglottic LMs may originate from the posterior wall and the walls of small blood vessels[5], and most of patients were admitted to the emergency department due to dyspnea. Dysphagia and foreign body sensation in the throat were also usual symptoms. The case we presented here is a supraglottic LMs. In addition, it is believed that although the malignant transformation of laryngeal LMs has not been reported, benign LMs must be distinguished from malignant leiomyosarcoma, and the mitotic rate is the most reliable standard indicating the malignancy of LMs [2].
To date, the treatment of LLMs has not been standardized due to its rarity, so treatment decisions are often made empirically from case to case. In these 16 case reports, the most recommended treatment is complete surgical resection through endoscopy (13 cases) or external surgery (3 cases). The method of surgery depends on the location of the tumor. Due to the large mass, 1 out of 16 patients with laryngeal LMs requires emergency tracheal intubation at the time of diagnosis. If the tumor seriously affects breathing, a tracheotomy should be performed first, and then the tumor can be removed through a neck approach. In addition, if the video laryngoscope shows a smooth surface and no new organisms with a pedicle, no biopsy should be taken to avoid bleeding. Recurrence after complete resection is rare, and only 3 literature reports recurrence in patients diagnosed with laryngeal LMs after surgery. Even though it is clear that no case of external incisions has reported perioperative complications or subsequent local recurrence, endoscopic surgery is still favored due to its less damage to tissues. With the development of transoral instruments, laser technology and low-temperature plasma in the past 20 years, it is not difficult to foresee that the treatment of laryngeal LMs will be more diverse.