Calcium pyrophosphate dihydrate crystal deposition disease mimicking malignant soft tissue tumor

Tophaceous calcium pyrophosphate dihydrate deposition disease of the knee mimicking an aggressive soft tissue tumour

Calcium pyrophosphate crystal deposition disease (CPPD), previously pseudogout, is the second most common crystal arthropathy after gout. There is increased radiographic prevalence associated with age, trauma and several metabolic disorders. Tophaceous CPPD (T-CPPD) is a rare form of CPPD which, though non-neoplastic, mimics a bone or soft tissue malignancy. T-CPPD usually presents as a mass in the temporomandibular joint and occasionally in the paraspinal tissues, but rarely in the joints of the extremities. We present an exceptionally rare case of T-CPPD that was subtle on plain radiography, presenting as a soft tissue mass in the knee joint.

Mimicry in older patients: tophaceous pseudogout as a tumorlike lesion: a case report

Pseudogout is frequently seen in painful arthritis of larger joints, especially the knees and shoulders. This case report describes a rare clinical entity of soft-tissue calcium pyrophosphate dihydrate crystal deposition disease surrounding the second metatarsal bone of an 81-year-old man with moderate painful swelling of the right forefoot for 2 years. Diagnostic imaging demonstrated a calcified soft-tissue tumor adjacent to the second metatarsal bone by considering a neoplastic process in the differential diagnosis. Excisional biopsy revealed a chalklike material on the calcified soft tissue that was pathognomonic for chondrocalcinosis or pseudogout. The excisional biopsy findings led to stagnation of the clinical symptoms, and no recurrence of the initial tumor was seen during 12-month follow-up. In the literature, only 28 cases of tophaceous pseudogout tumors in the extremities have been described. In these cases, the lesions were suspected of being chondrosarcomas. For this reason, a correct diagnosis has to be pursued by performing a biopsy to treat the disease correctly.

Tophaceous pseudogout in the knee joint mimicking a soft-tissue tumour: a case report

Tophaceous pseudogout in the knee joint is rare. We report an 82-year-old man who presented with a one-year history of pain and swelling of the right knee joint. Treatment with non-steroidal anti-inflammatory drugs and aspiration of the joint effusion had not been effective. The mass continued to enlarge, and the patient had difficulty walking. Radiographs and computed tomography showed meniscal calcification with an abnormal soft-tissue mass surrounded by calcification. After excision, massive calcified deposits were seen both inside and on the surface of the tophaceous pseudogout. The deposits showed birefringence under polarised light, suggestive of calcium pyrophosphate dihydrate crystals. At the 2-year follow-up, the patient could walk independently without knee pain or swelling, although his range of knee motion was slightly limited due to joint contracture that developed before surgery.

Median nerve and ulnar nerve palsy caused by calcium pyrophosphate dihydrate crystal deposition disease: case report

Calcium pyrophosphate dihydrate crystal deposition disease can cause extra-articular pathology including nerve compression syndrome. We report a rare case of this complication in a 79-year-old woman.