Cutting the Gordian Knot: Rare Presentation of Nodular Fasciitis as Supraclavicular Swelling with Muscular Involvement in 68Ga-FAPI-PET/CT

Abstract

Background: Nodular fasciitis is a benign, singularly occurring nodular fibroblastic/ myofibroblastic neoplasia. Due to the rapid growth and cellular atypia, this rare differential diagnosis in the head and neck region can be mistaken for malignant sarcomas. Methods: We present a 40-year-old female patient with an unclear, rough, and poorly displaceable supraclavicular swelling on the right as part of a medical check-up. Sonographically, the lump was poorly circumscribed with little vascularization. A consecutive core needle biopsy of the lesion yielded inconclusive results showing spindle-shaped tumor cells. 68Ga-FAPI-PET/CT showed an intensive uptake of the right supraclavicular lesion in addition to postoperative changes in the right tonsil. Subsequent operative partial excision of the lesion confirmed the histopathological diagnosis of nodular fasciitis. Results: Nodular fasciitis is the most prevalent pseudosarcoma found in soft tissues. This case is the first description of 68Ga-FAPI-PET/CT in nodular fasciitis. Surgical removal is advised; nevertheless, the tumor frequently diminishes on its own, and recurrence is rare. Extensive surgical therapy is not necessary. Conlcusions: The recognition of nodular fasciitis and its benign characteristics is crucial to prevent diagnostic errors and the subsequent unnecessary operative treatment of the patient.