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

Suspected intra-articular soft-tissue tumours and tumour-like lesions: Performance of image-guided core needle biopsy

PURPOSE

To determine the efficacy of image-guided core needle biopsy (IGCNB) in patients presenting with suspected intra-articular soft tissue tumours or tumour-like lesions.

METHODS

Retrospective study of patients referred to a musculoskeletal oncology service between January 2019 and May 2020 with a suspected intra-articular soft tissue tumour over a 16-month period. Data collected included patient age, gender, joint involved and maximal lesion size. Type of image-guidance (ultrasound or computed tomography), type of needle and type of anaesthesia, general anaesthetic (GA) or local anaesthetic (LA), were recorded, as was the histological diagnosis. For patients who proceeded to surgical excision, the IGCNB histology result was correlated with resection histology. Descriptive statistics were used and complications were also noted.

RESULTS

By the termination of data collection 91 patients underwent IGCNB, 32 (35.2 %) males and 59 (64.8 %) females with a mean age of 41.4 years (age range 3-86 years). The joints involved were the knee (n = 73; 80.2 %), ankle (n = 12; 13.2 %), hip (n = 3; 3.3 %), shoulder (n = 1; 1.1 %), elbow (n = 1; 1.1 %) and wrist (n = 1; 1.1 %). Biopsy types were as follows: US-guided GA (n = 29; 31.9 %), US-guided LA (n = 37; 40.7 %), CT-guided GA, (n = 23; 25.3 %), CT-guided LA (n = 2; 2.2 %). Mean maximal tumour dimension for 76 focal lesions was 36.5 mm (range 18-113 mm). IGCNB yielded a definitive histological result in 85 of 91 cases (93.4 %), 44 of whom went on to surgical resection. Concordance between IGCNB and resection histology was achieved in 42 of 44 cases (95.5 %). The commonest diagnosis was tenosynovial giant cell tumour, with only a single malignant lesion identified. There were no recorded immediate or delayed complications.

CONCLUSIONS

IGCNB of suspected intra-articular tumours or tumour-like lesions is a highly effective and safe technique.

An Unusual Case of Huge Tophaceous Pseudogout Mimicking as a Tumor-Like Lesion around the Ankle Joint: A Case Report and Literature Review

Pseudogout or calcium pyrophosphate dihydrate deposition disease (CPPD) primarily affects the joints and the periarticular tissues. Tophaceous or tumoral pseudogout is a rare form of this disease which is seen around the joints of extremities. It can be misdiagnosed as a neoplastic condition because of its clinicoradiological similarities, and thus, a proper histopathological examination is indispensable. We report one such case of extra-articular deposition of the CPPD crystals in a 65-year-old man who presented with an asymptomatic swelling around the left ankle. Radiographs showed a dense homogenous calcification, and FNAC revealed dense calcium deposits with numerous rhomboid-shaped crystals. It was managed by en bloc excision, and postoperative biopsy reports confirmed the diagnosis. Possibility of pseudogout should be kept as a differential diagnosis in patients presenting with calcified soft tissue swellings and should be subjected to a detailed histopathological examination for confirmation.

Temporal mandibular joint chondrocalcinosis (tophaceous pseudogout) diagnosed by ultrasound-guided fine-needle aspiration

Tophaceous pseudogout is a calcium pyrophosphate dihydrate crystal (CPPD) deposition disease that frequently affects elderly patient in the temporomandibular joint (TMJ). A diagnosis of CPPD deposition disease in the TMJ is challenging due to its mimicking of other benign and malignant entities. Surgical exploration followed by histologic examination is by far the most frequently used diagnostic modality. We present a case of an 87-year-old female who presented with a right TMJ mass. A final diagnosis of tophaceous pseudogout was made on cellular material obtained by ultrasound-guided fine-needle aspiration (US-guided FNA). Based on our case and current available literature, ultrasound-guided FNA is a reliable tool for diagnosing tophaceous pseudogout of the TMJ.