Intra-muscular Nodular Fasciitis Presenting as Swelling in Neck: Challenging Entity for Diagnosis

The diagnosis of Nodular Fasciitis is a very challenging on cytological aspirations. Even in histopathological sections, it can be sometimes be mistaken for soft tissue sarcomas due to its high cellularity, presence of mitotic figures, poor circumscription and degenerative myxoid areas. Most commonly, nodular fasciitis is seen on extremities; and sub-cutaneous form is most common. We are hereby reporting a case of nodular fasciitis at a rare site (head and neck area) in its rare form (intra-muscular type: originating within sternocleidomastoid muscle), which was clinically suspected as a malignancy arising from solitary thyroid nodule. Cytological diagnosis was issued as benign spindle cell lesion (where chances of a misdiagnosis as malignant are very high), thereby preventing radical surgery. It was subsequently confirmed as intra-muscular nodular fasciitis after histopathological examination.