INTRODUCTION: Metallosis is a condition characterized by an infiltration of periprosthetic soft tissues and bone by metallic debris resulting from wear or failure of joint arthroplasties. PRESENTATION OF CASE: Authors describe a case of a 45-year-old man treated for an osteosarcoma of the distal femur with a modular prosthesis when he was 18 years old, he developed massive metallosis with skin dyspigmentation after 17 years. His medical\surgical history was remarkable for a left tumoral knee prosthesis implanted 21 years ago. Two years before revision, the patient had a car accident with a two-points prosthesis breakage and despite the surgeon’s advice, the patient refused surgery. In two years, prosthesis malfunction caused a progressive catastrophic soft tissues infiltration of metallic debris. DISCUSSION AND CONCLUSION: Authors suggest that if prosthesis fracture is detected, revision surgery should be attempted as earlier as possible. Highlights:

Giant Cell Tumor of Bone is a benign tumor with high local aggressive expansion, which, in rare cases, spreads metastasis. Surgical treatment, which often consists of wide curettage to reduce recurrence risk, can lower the quality of life for those affected. Along with aggressive surgery, adjuvant intraoperative techniques have been implemented such as PMMA and cryotherapy. One of the most widely used cryotherapy techniques involves the use of probes to generate ice balls, which have been scientifically shown to have various impacts on the tumor. Although this has been acknowledged, no one has yet tested a way to accurately plan the positioning of cryotherapy probes before surgery, according to the research conducted by the authors. CRIO2AR is a randomized clinical prospective ongoing study by which it will be experimented via preoperative planning of ice probes placement using AR and 3D printing technologies. By studying a single clinical case with these technologies, the surgeon gains better awareness of patient’s anatomy and tumor localization. Preliminary results are shown in the article. The first results are confirming that these technologies are applicable in clinical practice. Secondly, preoperative planning is proving to be reliable, easily replicable, and useful for the surgeon.

Background: Granular cell tumors (GCTs) are rare neoplasms that may also involve the musculoskeletal system and peripheral nerves of the extremities. In these locations, their clinical presentation, management, and outcomes remain poorly characterized. Methods: A systematic review was conducted according to PRISMA guidelines. PubMed, MEDLINE, EMBASE, and Scopus were searched for articles published between 1975 and 2025 reporting GCTs arising from the musculoskeletal system or peripheral nerves, with available data on clinical presentation and treatment. Tumor location and size, symptoms, treatment modality, and oncological outcomes (recurrence or metastasis) at the latest follow-up were extracted. Results: Forty articles describing 67 cases were included (50 females, 17 males). Tumors showed benign (47) or atypical (2) behavior in 49 cases and malignant features in 18 cases. The mean largest tumor diameter was 44 mm, and malignant lesions were significantly larger than benign ones. Thirty-one lesions were located in the lower limbs, 25 in the upper limbs, and 11 had central musculoskeletal localizations. Swelling was the most common presenting symptom (92%), followed by pain (40%). Surgical excision was performed in all patients except one, who underwent primary amputation. Adjuvant chemotherapy or radiotherapy was sporadically used in malignant cases (two cases each). Among the malignant cases with reported oncological follow-up, 44% developed distant metastases, and one (5.6%) also experienced local recurrence. Only one benign GCT recurred (2%), whereas all other non-malignant lesions remained CDF (98%). Conclusions: Although rare, GCTs should be considered in the differential diagnosis of musculoskeletal soft-tissue tumors, given their potential for malignant behavior and metastatic spread.