Collagenous fibroma (desmoplastic fibroblastoma) presenting as a parotid mass

We describe the case of a 50-year-old man who was found to have a painless, slow-growing parotid mass of 10 months duration. At surgery, a well-delimited, lobulated 4x5-cm tumor was located on the deep lobe of the left parotid gland, adhering to the parotid sheath and masseteric fascia. Follow-up 6 years later has shown no evidence of recurrence. Cardinal morphologic features included multiple nodules of sparsely distributed stellate-or spindle-shaped fibroblasts within a collagenous or myxocollagenous stroma. Fascial involvement and entrapment of salivary gland were focally identified at the edges. Tumor cells were diffusely positive for vimentin with faint focal staining for alpha-smooth muscle actin. These findings satisfied the diagnostic criteria for collagenous fibroma (desmoplastic fibroblastoma). Ours represents the first report of this tumor type mimicking a parotid tumor.