Reason: Include ankle and mid foot. Assess lateral posterior superior calcaneal cyst. Ganglion vs reactive bursitis History: pain and swelling and increasing in size There is an ovoid mass within the soft tissues lateral to the Achilles tendon at its insertion on the calcaneus, corresponding to soft tissue opacity seen on prior radiographs. It measures approximately 13 x 8 mm in transverse dimension and approximately 15 mm in craniocaudal dimension. It is of similar signal intensity to muscle on non-fat-suppressed T1-weighted images, and is slightly hyperintense to skeletal muscle on fat-suppressed T1-weighted images. It is hyperintense on the fat-suppressed proton density weighted sequence, but is isointense to skeletal muscle on the STIR sequence. The mass enhances homogeneously following contrast administration. The mass abuts the lateral margin of the distal Achilles tendon and posterior calcaneus, but does not deform or invade either of these structures. The mass lies posterior to the sural nerve and lesser saphenous vein. We see no additional soft tissue masses. Bone marrow signal intensity is normal. We see no tenosynovitis or other significant tendon abnormalities.
Enhancing soft tissue mass along the lateral margin of the Achilles at its insertion on the calcaneus. This does not have the typical appearance of a cyst, ganglion or bursa, and its uniform enhancement suggests a solid tumor. Although the signal intensity of the mass is relatively low on the STIR sequence, overall the characteristics of this lesion are nonspecific, and tissue sampling is recommended. 