Achilles tendon nodule: inflammation, rupture, or tumor?

When an active patient has a mass on the Achilles tendon, fibroma of the tendon sheath should be in the differential diagnosis along with other tumors and benign conditions like inflammation or rupture. A case report demonstrates how the clinical characteristics of fibromas resemble other common tendon tumors, such as giant cell tumor of the tendon sheath. A histologic exam is needed to distinguish a fibroma of the tendon sheath from other tumors. Plain films should be considered to rule out bony involvement. Surgical excision is required. Patients should know that fibromas recur in 25% of those who have them removed.