Extraskeletal Myxoid Chondrosarcoma of the Jugular Foramen in a Pediatric Patient: A Case Report and Comprehensive Review of the Literature.

INTRODUCTION: Extraskeletal myxoid chondrosarcoma of the jugular foramen is a rare clinical entity, especially in the pediatric population. Thus, it can be confused with other pathologies. CASE PRESENTATION: We report an extremely rare case of a 14-year-old female patient with jugular foramen myxoid chondrosarcoma that was completely removed through microsurgical resection. CONCLUSION: The primary purpose of the treatment is gross total resection of the chondrosarcomas. However, adjuvant methods such as radiotherapy should additionally be applied in patients who have high-grade diseases or cannot undergo gross total resection because of anatomic localization.

Oncological and functional outcomes of planned and unplanned excision of soft tissue sarcoma: A retrospective study.

BACKGROUND: In soft tissue sarcomas, the oncological and functional outcomes between planned excision and unplanned excision with additional wide resection remains controversial. The purpose of this study is to determine the impact of unplanned excision on oncological and functional outcomes. METHODS: A retrospective single-center study was performed. Patients with soft tissue sarcoma surgically treated in 2005-2019 were included in this study. A total of 120 patients consisting of planned excision (PE) group (n = 88), and unplanned excision (UE) group (n = 32) were included. Overall-survival (OS), local recurrence-free survival (LRFS), metastasis-free survival (MFS), disease-free survival (DFS), incidence rate of reconstructive surgery and musculoskeletal tumor society (MSTS) score were assessed. Propensity score matching method was used in statistical analysis. RESULTS: The 5-year survival rate of OS, LRFS, MFS, and DFS did not differ between the PE and UE groups, however, rates of reconstructive surgery were higher in the UE group (PE: 48% vs. UE: 84%, p < 0.001). These results did not differ (PE: 41% vs. UE: 82%, p = 0.012) after propensity score matching was performed to align the backgrounds with difference in tumor size and depth. For MSTS score, the total score and "pain" and "emotional acceptance" scores were higher in the PE group before propensity score matching. The "pain" and "emotional acceptance" scores were higher in the PE group after propensity score matching also. CONCLUSIONS: Unplanned excision did not deteriorate oncological outcomes, however unplanned excision lead to unnecessary reconstructive surgery. Unplanned excision adversely affected patient-reported outcomes without worsening pure functional outcomes.

Secondary Extra-anatomic Infrainguinal Bypass following Lower Limb Tumoral Resection.

BACKGROUND: Soft tissue malignancy of lower limb can involve femoral triangle by direct tumoral invasion or secondary to ganglionic metastasis. Secondary arterial complications can appear during follow-up after initial tumoral resection and local radiation therapy. The aim of this study is to report our experience of secondary extra-anatomical lower limb revascularization following lower limb oncological resection with femoral bifurcation involvement. METHODS: This is a retrospective monocentric study including patients who underwent extra-anatomical iliopopliteal bypass, with a previous treated neoplasia involving homolateral femoral bifurcation. Proximal anastomosis was performed on the iliac artery, tunnelization was made through iliac wing, and distal anastomosis was done on distal superficial femoral or popliteal artery. RESULTS: Five patients underwent extra-anatomic iliopopliteal bypass for oncological purpose from 2008 to 2018 at our institution. Mean age at surgery time was 52 years (standard deviation = 19.3). Prosthetic graft was used in all cases. Primitive tumor involved Scarpa triangle in 3 cases (soft tissue sarcomas) and ganglionic metastasis involved Scarpa triangle in 2 cases (epidermoid carcinoma). Clinical presentation was ischemic in 4 cases and hemorrhagic in 1 case. One patient died during hospitalization. Of the 4 survivors, 3 patients had a patent bypass at the end of follow-up (2 had bypass thrombectomy, 1 patient had major amputation). CONCLUSIONS: Secondary iliopopliteal bypasses through the iliac wing following lower limb tumoral resection have acceptable results. It is a valid option for limb salvage especially after local radiation therapy and tumoral resection. Multidisciplinary management is necessary to obtain acceptable results and follow-up is mandatory.

Myxoid chondrosarcoma extraskeletal in pelvis location : a case report.

BACKGROUND: The extraskeletal myxoid chondrosarcoma (CME) is a rare tumor of the soft tissue, with clinically distinguishable clinical, histological, immunohistochemical, cytogenetic and evolutionary characteristics with an unfavorable long-term prognosis. CASE: We reported the case of a young patient of 18 years, accusing pelvic pain for 5 months with a poor general condition, an MRI was performed immediately, objective infiltrative mass endopelvic evoking several etiologies. The histology of the biopsy extraskeletal myxoid chondrosarcoma reveals a (CME). 's Staging came back normal. We performed an incomplete surgical resection due to the deep location of the pelvis in the tumor followed by radiotherapy. CONCLUSION: The CME is a tumor diagnosis very difficult and often delayed, despite a mostly local aggressiveness and prolonged survival, it is considered a low-grade sarcoma malignancy or intermediate malignancy. Treatment consists of complete surgical resection with a potential adjuvant radiotherapy . Chemotherapy is not very effective.

A case of diffuse infiltrating gastrointestinal stromal tumor of sigmoid colon with perforation.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract, and typically present as discrete well-circumscribed but non-encapsulated tumor masses. In this report, we describe a case of colonic perforation caused by an unusual form of GIST. A 72-year-old Japanese woman presented to the emergency department with acute abdominal pain. Under the provisional diagnosis of sigmoid colon perforation, a laparoscopic sigmoidectomy was performed. Although the tumor mass was undetectable during the preoperative examination, a spindle cell lesion with a diffuse longitudinal growth pattern replacing the muscularis propria was revealed by microscopic examination. The spindle cell lesion was exposed at the perforation, suggesting a causal relationship between the lesion and the perforation. The spindle cell lesion was KIT-positive and had a mutation in the C-KIT gene at exon 11. We diagnosed it as diffuse infiltrating GIST. We consider that the lesion would be a cause of the colonic perforation, and emphasize the importance of accurate diagnosis of the lesion by histological, immunohistochemical and genetic examinations.

Extraskeletal myxoid chondrosarcoma arising in the femoral vein: a case report.

Soft tissue tumors arising in deep veins of the extremities are uncommon, although a few cases of synovial sarcoma or leiomyosarcoma arising in the femoral vein have been documented. However, to the best of our knowledge, an extraskeletal myxoid chondrosarcoma (EMC) arising in the femoral vein has not been reported in the English literature. We report a case of EMC arising in the femoral vein of a 70-year-old man who presented with right leg edema and was diagnosed with a deep venous thrombosis (DVT) by computed tomography (CT). Magnetic resonance imaging (MRI) revealed a mass in the right proximal thigh that was diagnosed as myxomatous sarcoma by aspiration cytology, and anticoagulant therapy was initiated. The mass was surgically resected en bloc, including the femoral vein and surrounding soft tissue, and the femoral artery was preserved. The femoral vein was not reconstructed. The histologic diagnosis was an extraskeletal myxoid chondrosarcoma. The patient received postoperative local radiation treatment, with a total dose of 60 Gy, and is currently doing well with no evidence of local recurrence or metastasis at 8 months after surgery. In summary, this case report shows that EMC can arise in the femoral vein, and that reconstruction of the femoral vein is not always necessary during surgery for soft tissue tumors.

[Extraskeletal myxoid chondrosarcoma: a report of 5 cases and review of literature].

OBJECTIVE: To study the clinicopathologic features, immunophenotype and differential diagnosis of extraskeletal myxoid chondrosarcoma (EMC). METHODS: The clinicopathologic features of 5 cases of EMC (during the period from 2008 to 2013) were retrospectively analyzed. Immunohistochemical study (EnVision method) was carried out using the archival material. The literature was reviewed. RESULTS: There were altogether 3 female patients and 2 male patients. Their age ranged from 38 to 63 years (average = 51 years). The patients primarily presented with a tender soft tissue mass. All the tumors studied were solitary and the duration of disease onset varied from 3 months to 1 year. The sites of involvement included toe (number = 2), intracranial (number = 1), thigh (number = 1) and shoulder (number = 1). Gross examination showed white nodular masses with a gelatinous cut surface. The average tumor size measured 5.2 cm in greatest dimension. Histologically, a multinodular architecture with fibrous or loose fibrovascular septa separating lobules of tumor cells was identified. The lobules contained abundant myxoid stroma, with peripheral accentuation of tumor cellularity. Two cases were diagnosed as cellular variant of EMC, with invasive growth pattern and hemorrhage. The tumor cells in cellular EMC were arranged in solid nodules, with rare myxoid matrix in between. The nuclei were relatively uniform, round to oval and contained prominent nucleoli. The mitotic figure ranged from 5 to 10 per 10 high-power fields. Immunohistochemical study showed that all of the 5 cases were positive for vimentin, mitochondria and CD56. Two cases expressed synaptophysin and NSE. Focal positivity for these neuroendocrine markers was detected in the other 2 cases. Chromogranin and S-100 protein expression was demonstrated in 2 cases. The staining for epithelial membrane antigen was positive in case 2 and negative in the other 4 cases. CD117 showed diffuse positivity in case 1, the other 4 cases were not expressed. CONCLUSIONS: EMC is a rare soft tissue sarcoma characterized by distinctive histopathologic features and often shows neuroendocrine differentiation. Although EMC is a slow-growing tumor, it carries a high local recurrence rate and even metastases, warranting long-term follow up.

[Cardiac metastase of a soft tissue sarcoma: a case report and a review of the literature]. / Métastase cardiaque d'un sarcome des tissus mous: cas clinique et revue de la literature.

Soft tissue sarcomas represent rare tumors. They recur most often locally and in the lungs. We report the case of a 58-year woman who was treated for awith chemotherapy and then surgery. About a year after the end of the treatment an intracardiac mass was identified during a follow up chest CT-scan. The patient underwent a surgical resection of that mass found to bel myxoid chondrosarcoma metastasis. Only 2 cases of cardiac dissemination of extraskeletal myxoid chondrosarcoma have been described. The differential diagnosis of intracardiac masses is discussed. In some carefully selected cases atrisks of obstructive shock or embolization and unique metastatic location, cardiac surgery should be considered.

The misdiagnosis of external auditory canal carcinoma.

External auditory canal (EAC) carcinomas are frequently misdiagnosed. The aim of this study was to conduct a review of misdiagnosed cases and analyze the factors involved. This study was a retrospective assessment. Eighteen of 44 EAC carcinoma cases seen at the Eye and ENT Hospital were misdiagnosed. All medical records were retrospectively analyzed for the age, sex, presenting symptoms, type of misdiagnosis, computed tomographic (CT) or magnetic resonance imaging (MRI) findings, stage of the cancer, surgical approach, histopathological examination, adjunctive therapy (postoperative radiotherapy) and outcomes of treatment. Six cases were misdiagnosed as otitis media, five cases were misdiagnosed as otitis externa, and two cases were misdiagnosed as external auditory canal cholesteatomas. Other misdiagnoses were stenosis of the EAC, ear neuralgia, furuncle of the EAC, benign neoplasm of the EAC and pre-auricular fistula. Our analyses suggest that a biopsy should be conducted to obtain a histopathological diagnosis if an EAC carcinoma is suspected, in case otitis media or otitis externa does not respond to routine anti-bacterials. Head and neck MRI should be used to explore the involvement of soft tissues. Patients with bloody ear discharge and otalgia, particularly with temporal bone erosion seen in a CT scan, are highly likely to have a malignant carcinoma of the temporal bone.

Phosphaturic mesenchymal tumor: a report of 6 patients treated at a single institution and comparison with reported series.

Osteogenic osteomalacia (OO)-associated phosphaturic mesenchymal tumors (PMTs) might represent a single histopathologic paraneoplastic entity. These tumors are largely misunderstood, ignored, or unknown by pathologists and clinicians. To elucidate the characteristics of OO-associated PMTs, we retrospectively analyzed the clinicopathologic features of PMTs from 6 patients, with either known OO or features suggestive of PMT-mixed connective tissue variant, who were studied and managed at a single center during the period from 1993 to 2011. Histologically, the tumor showed proliferation of spindle cells with focal areas of matrix production that showed distinct calcification, ossification, and osteoid-like matrix. Two patients had no evidence of disease and normal biochemical values; the other 2 patients each had multiple surgeries for multiple recurrences. In conclusion, PMT is histologically a benign lesion, with the malignant and metastatic variant being extremely rare. Infiltration of surrounding tissue is a frequent feature that is best managed with complete surgical removal of all involved tissue, which dramatically resolves the tumor-associated osteomalacia.

Intra-articular Extraskeletal EWSR1-Negative NR4A3-Positive Myxoid Chondrosarcoma: A Case Report.

CASE: Extraskeletal myxoid chondrosarcomas (EMCs) are rare soft-tissue malignancies. Intra-articular occurrence is even more rare. To our knowledge, this case is one of only 2 reported intra-articular EMC cases of the knee free of local recurrence and/or amputation at follow-up. This case is also distinctive for being fluorescence in-situ hybridization-negative for the typical EMC-balanced translocation t(9;22) which fuses EWSR1 with NR4A3, harboring instead a variant translocation resulting in fusion of NR4A3 with a less common gene fusion partner. CONCLUSION: This is a unique case of intra-articular EMC of the knee with a rare molecular fingerprint and an unusually positive outcome.

Extraskeletal myxoid chondrosarcoma of the leg in a child: A case report.

RATIONALE: Extraskeletal myxoid chondrosarcoma is a slow-growing soft tissue tumor of adults with a propensity for local recurrence and eventual metastasis. Only 17 pediatric and adolescent cases have been reported. PATIENT CONCERNS: Here we present an 11-year-old boy with a 3-year history of a slowly growing painless left leg mass. Magnetic resonance imaging of the lesion revealed a subfascial well-circumscribed lesion with intramuscular extension in the medial gastrocnemius muscle of the left leg. DIAGNOSES: He underwent wide local excision of the mass and the histomorphological and immunohistochemical findings were consistent with extraskeletal myxoid chondrosarcoma. INTERVENTIONS: Possible radiotherapy was the further management plan. OUTCOMES: He was in good condition with no evidence of recurrence at 6 months postsurgery. LESSONS: Although pediatric cases of extraskeletal myxoid chondrosarcoma were reported to be aggressive, the tumor in this case demonstrated indolent behavior. Furthermore, the tumor in this case showed primitive round cell foci which adds to a previous study that especially reported this morphology in pediatric cases.

Comparison of the diagnostic performances of core needle biopsy in myxoid versus non-myxoid tumors.

BACKGROUND: Despite the overall diagnostic utility of core needle biopsy (CNB) comparable to incisional biopsy, increased diagnostic errors have been suggested of CNB for myxoid soft tissue tumors. This study compared the diagnostic performance of CNB between myxoid and non-myxoid soft tissue tumors. METHODS: 369 patients who underwent ultrasound-guided CNB prior to resection for soft tissue tumors were classified into two groups according to resection pathology; myxoid group (n = 75) and non-myxoid group (n = 294). One-hundred and ninety-three patients were male and the median age of the patients was 40 years. Two-hundred and sixty-three tumors were malignant. RESULTS: CNB correctly diagnosed malignancy in 84% (58 of 69) for the myxoid group and 95% (184 of 194) for the non-myxoid group. For diagnosing histologic grade of soft tissue sarcoma, CNB correctly identified high grade in 78% (18 of 23) for the myxoid group and 74% (94 of 128) for the non-myxoid group. Correct diagnosis rate of histological type was significantly lower in the myxoid group (63% [47 of 75] in the myxoid group and 83% [242 of 294] in the non-myxoid group, p = 0.013). CONCLUSION: Our study suggests that CNB is useful for myxoid soft tissue tumors of the extremity, with regard to diagnosing malignancy and histologic grade. However, CNB was less useful for identifying histologic subtype in myxoid tumors than in non-myxoid tumors.

[Non-epithelial tumors of the large intestine]. / Nienablonkowe nowotwory jelita grubego.

UNLABELLED: Colorectal cancer may arise from any kind of tissue constituting normal wall of the large intestine, however, in majority of cases, it is of epithelial origin. Endocrine, mesenchymal neoplasms and non-granulomatic lymphomas belong to rarely occurring cancers of the large intestine. Mesenchymal neoplasms may derive from muscles, nervous system, fibrous connective tissue, fat tissue and from blood and lymphatic vessels. The paper presents 3 cases of non-epithelial neoplasms of the large intestine (myosarcoma and 2 myomas). All cancers concerned women older than 50 years (mean age 64.6 +/- 11.4 years) and were localized in the right hemicolon. In all cases episodes of hemorrhage from the lower part of the digestive tract triggered the diagnostic procedures. Surgical treatment varied from hemicolectomy with lymphadenectomy to endoscopic excision of a small lipoma. Histopathological verification and immunohistochemical staining were obtained after their removal. Clinical course and intraoperative situation were decisive as to type of surgery. Although mesenchymal tumors are very rare among large intestine neoplasms, one should consider their occurrence while carrying preoperative diagnosis. CONCLUSION: Occurrence of other tumors than neoplasms should be taken into consideration while carrying preoperative diagnosis.

Well-differentiated extraskeletal chondrosarcoma: about a new case.

Extraskeletal chondrosarcoma is a rare malignant tumor. The well differentiated histological type, which is found primary in soft tissue, is extremely rare. This report  describes the case of a 58-year-old woman presented with a large palpable mass in the right buttock. Imaging studies revealed a well-defined soft tissue mass, with extensive calcification. A histological examination after surgical resection confirmed the diagnosis of well-differentiated extraosseous chondrosarcoma. The outcome was favorable, without recurrence or metastasis.

Cardiac inflammatory myofibroblastic tumor in interventricular septum: A rare case report.

RATIONALE: Cardiac inflammatory myofibroblastic tumor (IMT) is a rare primary cardiac tumor which is currently considered as a low-grade neoplasm. The tumor has a predilection in infants and adolescents and primarily occurs as an endocardial-based cavitary mass. However, cardiac IMT that only involves the interventricular septum in middle-aged adults is extremely rarely reported. Considering its infrequency, we report a rare clinical case, with the aim of sharing our experience during the diagnostic procedures. PATIENT CONCERNS: A 45-year-old, previously healthy female, with no medical history was admitted to the outpatient clinic due to the identification of an abnormal radiographic finding during a routine health examination. DIAGNOSIS: Transthoracic echocardiography (TTE) revealed a 3.5 cm × 4.0 cm × 4.5 cm heterogeneous mass in the interventricular septum. Color Doppler echocardiography detected sparse blood flow signals inside the mass. Magnetic resonance imaging (MRI) confirmed a hyperintense T2-weighted, isointense T1-weighted mass. Three-dimensional (3D) TTE demonstrated a spherical mass in the middle part of the interventricular septum. Postoperative histopathological examinations revealed a mesenchymal tumor composed of scattered spindle myofibroblasts with a myxoid atypia, associated with infiltration of lymphocytes and plasma cells. INTERVENTIONS: Complete tumor resection was successfully performed via median sternotomy under general anesthesia. OUTCOMES: After surgery, the patient recovered successfully. The patient was in good general health without any clinical symptoms. The echocardiographic examination at the 12-month follow-up period revealed normal function of the heart, and there was no evidence of tumor recurrence. LESSONS: To our knowledge, cardiac IMT only the involving interventricular septum in a middle-aged adult has never been previously reported before. Echocardiography plays a critical role in establishing the primary diagnosis of cardiac IMT and evaluating regular follow-up examinations. Complete surgical resection of the mass is considered the first-line treatment despite the absence of symptoms.

Results and functional outcomes of en-bloc resection and vascular reconstruction in extremity musculoskeletal tumors.

OBJECTIVES: This paper aims to evaluate the extremity function and vascular outcome after limb-sparing surgery for extremity musculoskeletal tumors invading vascular structure required reconstruction. METHODS: Of the 507 patients with musculoskeletal tumors, who underwent surgery between 2004 and 2007, 17 (3,3%) patients with major vessel involvement were included in the study. The mean age was 37.8 ± 14.5, with a female/male ratio of 8/9. Thirteen (76.4%) patients had Stage IIb disease, and 2 (11,7%) patients had Stage III disease. In 2 (11,7%) patients have locally aggressive tumor that had Stage 3. Fifteen (88.2%) of the cases involved lower extremity, whilst 2 (11.8%) of them involved upper extremity. An arterial reconstruction was carried out in all patients. Wide tumor resection and endoprosthetic reconstruction were performed in 6 (35.2%) patients. Other 11 (65.8%) patients were treated with wide resection and soft tissue reconstruction. Postoperative data included; perioperative morbidities such as bleeding, infection, graft thrombosis, rupture, metastatic local recurrence and mortality. Ankle brachial index (ABI) and color-flow-duplex-scan (CFDS) were done at the final follow-up of the study, in order to prove the efficacy of reconstruction. Functional outcome was evaluated with International Society of Limb Salvage (ISOLS) criteria. RESULTS: The mean follow-up was of 39 months (range 3-120). Perioperative complications were arterial graft thrombosis occurred in 3 (17.6%) patients treated acutely with thrombectomy, uncontrolled deep wound infection occurred in 2 patients whom extremities were amputated. The most frequent complication after surgery was limb edema according to possibly venous and lymphatic obstruction, staged as C1, C2 and C3 disease was established in 6 patients (two patients in each group), and 1 patient was classified as C6 disease. Three (17.6%) patients had local recurrence (1/3 patient died and 2/3 (11.7%) patients underwent transfemoral amputation). At the last follow-up, 9 (52.9%) patients were alive without evidence of disease, 8 (47.1%) patients were died due to primary disease. There were 8 (47.1%) patients alive with an intact limb. Although functional outcome scores were satisfactory, emotional acceptance scores were low. The limb salvage probability was 74.0%. CONCLUSION: Limb-sparing oncological surgery in musculoskeletal tumors with vascular invasion provides a satisfactory limb function, which may lead to an improved life quality. Arterial reconstruction has a high rate of patency in the long term. The surgeon should be aware of early perioperative complication related to vascular reconstruction and infection that effect on the rate of extremity survival. LEVEL OF EVIDENCE: Level IV, Therapeutic study.

EWSR1-SMAD3-rearranged Fibroblastic Tumor: An Emerging Entity in an Increasingly More Complex Group of Fibroblastic/Myofibroblastic Neoplasms.

Three cases of superficial acral fibroblastic spindle cell neoplasms with EWSR1-SMAD3 fusion have been recently reported. Their differential diagnosis is broad, primarily comprising rare tumors from the fibroblastic/myofibroblastic category. The aim of this report is to present 4 new cases of this entity and to discuss the appropriate differential diagnosis. Also, as the ERG antibody seems to be a characteristic marker for these tumors, we analyzed ERG immunostaining characteristics in potential mimics of this entity. All cases in our cohort occurred in women aged 5 to 68 years (mean, 36.5 y). Two were located on the hand, 1 on foot, and the last case arose on the calf. The tumor size ranged from 1 to 1.5 cm in the greatest dimension, with a mean size of 1.2 cm. Except for one recent case, follow-up was available, ranging from 7 to 18 years (mean, 11.7 y), with a recurrence noted in 1 case after 10 years. All tumors were subcutaneous and showed 2 main components. One consisted of bland, spindled cells with elongated nuclei which were round when observed on the cross-section. These cells mostly grew in relatively hypercellular, well-organized, and intersecting fascicles. The second component was prominently hyalinized and paucicellular, but lacked calcifications. Both components showed either a distinct zonation pattern, or they were randomly intermingled with each other. In all 3 analyzable tumors, next-generation sequencing showed EWSR1-SMAD3 gene fusion in each case. By fluorescence in situ hybridization, one tested case also revealed unbalanced rearrangement of the EWSR1 gene. All 4 cases showed strong, diffuse nuclear expression of ERG, whereas none of the mimics stained with this antibody except for weak to moderate staining in calcifying aponeurotic fibromas (9/10 cases). Two tumors showed focal weak to moderate expression of SAT-B2. The 4 herein presented cases further broaden the clinicopathologic spectrum of tumors with EWSR1-SMAD3 gene fusion. They also confirm that they represent a novel entity for which we propose the name EWSR1-SMAD3-rearranged fibroblastic Tumor. Our study also proves that in the context of fibroblastic/myofibroblastic tumors, ERG immunohistochemistry is a relatively specific marker for these neoplasms.

Para-articular osteochondroma of the knee.

We report a case of para-articular chondroma located in the infrapatellar fat pad of the knee of a 42-year-old woman with a history of anterior knee pain and restricted range of motion. On clinical examination, a solid palpable mass in the infrapatellar region was detected. Radiography and computed tomography of the knee revealed the presence of 3 different "popcorn"-like gross calcifications within Hoffa's fat pad. Magnetic resonance imaging showed areas of signal intensity in Hoffa's fat pad that were consistent with calcific nodules surrounded by chondral tissue. During arthroscopy, a dense extrasynovial mass was discerned within Hoffa's fat pad. The mass was entirely removed through an open approach medial to the patellar tendon. Resection specimens consisted of 3 well-circumscribed nodules of 5 x 2.5 x 1.5, 2 x 2 x 1, and 1.5 x 2 x 1 cm, respectively. Grossly, these nodules were surrounded by adipose tissue and presented a thin fibrous membrane. Histologic examination showed that the nodules were composed of cartilaginous tissue surrounded by fibrous connective and adipose tissue with multifocal endochondral ossification. The precise pathogenetic mechanism of these tumors remains unknown, but cartilaginous metaplasia of articular and para-articular connective tissue seems to be the primary cause. Patients with these lesions are currently treated with the use of marginal resection or excision.