Durable clinical response to radiotherapy in an unresectable masticator space nodular fasciitis: a case report

Background: Nodular fasciitis is a benign myofibroblastic proliferation characterized by rapid and infiltrative growth pattern and is often misdiagnosed as a malignant neoplasm. The standard treatment is complete surgical excision resulting in good outcomes. Only two cases of head and neck nodular fasciitis receiving radiotherapy (RT) have been reported. The role of RT for nodular fasciitis remains unclear. To our knowledge, this is the first reported case of head and neck nodular fasciitis treated with primary RT due to unresectability and lack of other treatment options that resulted in a durable and good radiologic and symptomatic response without late toxicity. Case Description: A 67-year-old male was diagnosed with extensive left masticator space nodular fasciitis deemed unresectable by a head and neck surgeon. Oral corticosteroids were discontinued due to poor response and impaired blood glucose control. Complaining of severe oral intake impairment due to oral cavity obstruction, RT was offered due to lack of available treatment options. He underwent intensity-modulated radiation therapy (IMRT) receiving 50 Gy in 200 cGy daily fractions given over 6 weeks to the gross lesion. RT plan prioritized normal tissue constraints. Treatment was well tolerated with grade 1 mucositis being the only acute toxicity. At 2-month post-RT, regression of the mass afforded relief of oral passage obstruction and oral intake impairment. At 3- and 4-month post-RT, there is near total resolution with no radiation mucositis or dermatitis. Surgery was advised but still no consent; he opted for observation and close monitoring. At 10-month post-RT, the oral cavity component is no longer seen. No long-term toxicities such as trismus, chronic mucositis, dermatitis, xerostomia, dysgeusia, nor xerophthalmia were noted. Conclusions: While complete excision remains the standard treatment for nodular fasciitis, this may not be an option in cases with extensive disease involvement. This article reported that RT as the primary treatment for unresectable head and neck nodular fasciitis can lead to favorable clinical outcomes. Nonetheless, this emphasizes the importance of a multidisciplinary approach in managing such cases and underscores the necessity to apprise the patient of the risks and benefits of RT.