Nodular fasciitis of the masseter

A 73-year-old man presented to ENT clinic with a painless, smooth lump overlying his right cheek. Fine needle aspiration wrongly diagnosed necrotising malignancy with squamous differentiation. MRI showed a lesion overlying the right masseter, and positron emission tomography scanning incorrectly suggested this was a metabolically active lymph node. After surgical excision, immunohistochemical analysis showed this was in fact nodular fasciitis of the masseter. Nodular fasciitis is a rare, benign, proliferative lesion whose clinical and histological features make it difficult to distinguish from malignancies such as sarcoma. Immunohistochemical analysis for markers including vimentin and actin is crucial for diagnosis. Without this, misdiagnoses are common and patients are at risk of unnecessarily aggressive treatment. This case report summarises the epidemiological, aetiological and clinical features of nodular fasciitis, explores the pitfalls of investigation modalities and describes its management.