Differentiated thyroid cancer (DTC) is relatively rare and can metastasize to both the lungs and bones. The great majority of bone metastases occur in red marrow regions where blood flow is high. Only one patient has been described with direct DTC metastasis to the subchondral bone of the femoral head. The patient was a 68-year-old Japanese female who had presented with left hip joint pain at age 63 years. At age 51 years, she had been diagnosed with DTC and underwent partial excision. X-rays showed partial femoral head collapse, suggesting osteoarthritis or idiopathic necrosis of the left femoral head. Three years later, a 131 I whole-body scan showed accumulation in the left femoral head, resulting in a diagnosis of DTC metastasis to the left femoral head. Bipolar hip arthroplasty was performed. Examination of the excised femoral head resulted in a final diagnosis of metastasis of follicular thyroid cancer, which was limited histopathologically to the subchondral bone of the femoral head. Tumor metastasis to the subchondral bone of the femoral head is exceedingly rare. Overall survival of patients with bone metastasis is improved by complete resection. Differential diagnosis of patients with a previous history of DTC who present with femoral head collapse should include bone metastasis of DTC.

Chondroid lipoma, first described in 1993 by Meis and Enzinger, is a very rare lipomatous tumor. Because it is a benign tumor, it does not require radiotherapy, chemotherapy, or extensive resection. However, histologically, it is often confused with a sarcoma. It is crucial to differentiate chondroid lipoma from sarcoma to avoid choosing an inappropriate treatment strategy. Although MRI, radiography, and ultrasound have been used to evaluate chondroid lipomas, imaging cannot accurately differentiate chondroid lipoma from sarcoma. A 39-year-old man presented to a local clinic with a 1-month history of a painless mass in his left neck. Results of a needle biopsy suggested an atypical lipomatous tumor, and the patient was referred to our hospital. Physical examination revealed a hard and mobile mass in the left neck. Plain X-ray radiographs showed an absence of calcification in the soft tissue mass. MRI revealed a well-defined and lobulated mass, and on T1-weighted images, the lesion showed heterogeneity, with higher signal intensity than that of muscle. On T2-weighted images, the septum had low-signal intensity. On T2-weighted fat-suppressed images, the signal of the mass was completely suppressed. The SUVmax of the mass on FDG PET was 1.84. An additional needle biopsy was performed, and on the basis of the results, we arrived at a diagnosis of well-differentiated liposarcoma. The mass was resected marginally. Macroscopically, the mass was encapsulated and markedly harder than well-differentiated liposarcoma. Histologically, the tumor was composed of myxoid and cartilaginous matrix, and mature fat cells and lipoblast-like cells were present. The final diagnosis was chondroid lipoma, and no recurrence was observed 1 year after surgery. Chondroid lipoma is an extremely rare benign soft tissue tumor that is often confused with sarcoma. It is very important to differentiate chondroid lipoma from sarcoma when the SUVmax value of the mass is low, even when biopsy results suggest that it is a sarcoma.

Ewing’s sarcoma is a primary malignant tumor of bone occurring mostly in childhood. Few effective reconstruction techniques are available after wide resection of Ewing’s sarcoma at the distal end of the tibia. Reconstruction after wide resection is especially difficult in children, as it is necessary to consider the growth and activity of the lower limbs. A 12-year-old Japanese boy had presented with right lower leg pain at age 8 years. Imaging examination showed a bone tumor accompanied by a large extra-skeletal mass in the distal part of his tibia. The tumor was histologically diagnosed as Ewing’s sarcoma. The patient received chemotherapy, followed by wide resection. Reconstruction consisted of a bone transport method involving external fixation of Taylor Spatial Frame. To prevent infection after surgery, the external fixation pin was coated with iodine. One year after surgery, the patient showed poor consolidation of bone, so iliac bone transplantation was performed on the extended bones and docking site of the distal tibia. After 20 months, tibia formation was good. Three years after surgery, there was no evidence of tumor recurrence or metastases; bone fusion was good, and he was able to run. The bone transport method is an effective surgical method of reconstruction after wide resection of a bone tumor at the distal end of the tibia, if a pin can be inserted into the distal bone fragment. Coating external fixation pins with iodine may prevent postoperative infection.

Limb salvage surgery is the standard treatment for malignant bone and soft tissue tumors of the lower extremities. Frozen autografts treated with liquid ni

Unplanned excision (UE) of soft tissue sarcoma (STS) carries a high risk of local recurrence; additional wide excision is generally recommended. Some patients cannot undergo early re-excision because of patient preference, delayed referral, or an undefined extent of resection, and are observed instead. We retrospectively reviewed 32 patients with STS who had undergone UE at previous hospitals, who first visited our institution between 1997 and 2024, and in whom immediate additional wide excision could not be performed. Recurrence-free survival (RFS) was estimated using the Kaplan–Meier method. Local recurrence was detected in 22 of 32 patients (68.8%) over a median follow-up of 65.3 months, with 63.6% of recurrences occurring within 12 months. The 1-, 3-, and 5-year RFS rates were 56.2%, 32.5%, and 32.5% (median, 1.26 years). Recurrence also developed in 3 of 6 grade 1 tumors. In sensitivity analyses excluding patients referred only after recurrence (n = 20) and restricted to referral within 90 days (n = 22), recurrence still developed in 50.0% and 59.1%. The 5-year overall survival rate was 96.0%. UE of STS carries a high risk of early local recurrence, even in low-grade tumors; additional wide excision should therefore be recommended whenever feasible.