Myofibromas are rare, benign tumors that arise from myofibroblastic cells and most frequently develop in the skin, subcutaneous tissue, muscle, or bone [1]. Although these lesions are predominantly observed in the pediatric population, adult cases have also been documented [2–4]. They can present in one of three forms: solitary, multicentric without visceral involvement, or multicentric with visceral infiltration [4]. Myofibromas are benign and typically exhibit an indolent course; however, recurrence has been reported in 7% to 31% of cases, particularly after incomplete resection or in multicentric presentations [3,5]. Long-term follow-up data indicate that solitary myofibromas, when completely excised, rarely recur and are associated with an excellent prognosis [3,6]. Although these tumors are relatively frequent in the head and neck region, involvement of the nasal cavity or paranasal sinuses is rare, and solitary lesions arising from the adult nasal septum are even less common [1]. We report an unusual case of a solitary myofibroma originating in the nasal septum of an adult, successfully treated with endoscopic transnasal resection.

A 69-year-old man was referred to our clinic with an incidentally discovered reddish mass in the right nasal cavity. He reported experiencing recurrent right-sided epistaxis for 1 month. His medical history included hypertension, atrial fibrillation, angina pectoris, and macular degeneration. Additionally, he had undergone endovascular coil embolization for a cerebral aneurysm 17 years earlier. Endoscopic examination revealed a well-circumscribed, vascular mass situated between the right middle turbinate and the nasal septum (Fig. 1A). Paranasal sinus computed tomography showed a 1.8×1.5 cm enhancing mass occupying the posterior nasal cavity and extending anteriorly to the sphenoid sinus, with associated deviation of the nasal septum to the left (Fig. 1B and C). Magnetic resonance imaging demonstrated a solid mass with intermediate signal intensity on T1-weighted images (T1WIs), heterogeneous high signal intensity on T2WIs, and moderate enhancement on gadolinium-enhanced T1WIs (Fig. 2).

The patient underwent endoscopic excision of the right nasal cavity mass under general anesthesia. The lesion, along with the surrounding healthy mucosa, was removed using a harmonic scalpel (Ethicon Endo-Surgery) and microdebrider (Medtronic Xomed), followed by cauterization with suction cautery to reduce the risk of recurrence (Fig. 3A). The tumor base was identified in the posterior portion of the right nasal septum (Fig. 3B). Histopathological evaluation revealed a biphasic growth pattern characterized by spindle-shaped tumor cells arranged around blood vessels, along with fascicles of variably hyalinized, myoid-appearing cells (Fig. 4A). Immunohistochemistry showed positivity for smooth muscle actin (SMA) (Fig. 4B) and negativity for desmin (Fig. 4C) and CD34 (Fig. 4D), findings consistent with myofibroma. The patient experienced an uneventful recovery, and the epistaxis resolved completely. Endoscopic examinations conducted 2 years after surgery demonstrated no evidence of recurrence (Fig. 5).

Myofibromas, whether solitary or multicentric, are benign soft-tissue tumors most frequently observed in children [3]. When systemic involvement is present, the condition is referred to as myofibromatosis [4]. Multicentric cases often demonstrate familial inheritance patterns, whereas solitary lesions typically occur sporadically [1,7]. Solitary myofibromas are reported to be at least twice as common as multicentric variants [6], with a slight male predominance and frequent occurrence in the head and neck region [4]. Most previously documented cases have involved children or young adults, with solitary lesions more commonly arising in the maxillary sinus, nasal cavity, and oral cavity [4,5]. However, solitary myofibromas of the adult nasal septum remain exceptionally rare.

The clinical manifestations of nasal myofibromas are nonspecific and resemble those of other sinonasal neoplasms. Symptoms vary depending on tumor location, size, and growth rate. Patients most often present with nasal obstruction, discomfort, or epistaxis. Solitary lesions, being benign and slow-growing, seldom cause pain [3,5]. In the present case, the patient’s chief complaint was recurrent epistaxis, with the tumor arising from the posterior nasal septum.

A definitive diagnosis requires both histopathological and immunohistochemical evaluation. The differential diagnosis of spindle cell tumors in the nasal septum includes schwannoma, solitary fibrous tumor (SFT), and glomangiopericytoma. Schwannomas typically demonstrate Antoni A and B patterns and are immunoreactive for S-100 protein. SFTs usually show CD34 and STAT6 positivity, while glomangiopericytomas display perivascular myoid cell proliferation with variable SMA expression and are frequently positive for β-catenin [8]. Microscopically, myofibroma exhibits a distinctive biphasic morphology [2,6]. Peripheral areas are composed of spindle-shaped cells arranged in fascicles or whorls, whereas the central regions contain more cellular zones with oval cells surrounding branching vessels, creating a hemangiopericytoma-like pattern [1]. Immunohistochemistry typically reveals positivity for SMA and muscle-specific actin, with variable or absent desmin staining [5]. Lack of CD34 expression assists in excluding SFTs [9]. These features are essential for distinguishing myofibroma from other spindle cell neoplasms. In our case, additional immunohistochemical markers such as Ki-67, β-catenin, or STAT6 were not assessed. Nonetheless, the diagnosis was supported by characteristic biphasic histological findings and immunoreactivity for SMA, with negativity for desmin and CD34. Although PDGFRB mutations have been increasingly identified in infantile and familial myofibromatosis [10,11], molecular testing was not pursued here given the patient’s advanced age, solitary lesion, and lack of relevant family history.

Complete surgical excision remains the primary treatment for sinonasal solitary myofibromas [2,7]. In this case, the mass was successfully resected via a minimally invasive endoscopic approach, achieving total removal. Prognosis is influenced by tumor size and anatomical location, yet recurrence is rare following complete excision [3]. Despite its rarity, myofibroma should be included in the differential diagnosis of nasal septal masses in adults. Surgical management typically yields excellent outcomes with a low risk of recurrence.