Pigmented Villonodular Synovitis: Potential Pitfall on Oncologic 18F-FDG PET/CT

Pigmented Villonodular Synovitis: A Metastatic Melanoma Imitator

ABSTRACT

A 45-year-old woman with a history of previously treated left plantar foot melanoma presented with a left thigh mass. Fine needle aspiration findings were concerning for metastatic melanoma (MM). Imaging was remarkable for PET-avidity of both the biopsied thigh mass and of a left posterior knee nodule. The knee nodule was also enhancing on MRI, concerning for a site of metastasis. Resection of the thigh mass and intra-articular nodule was performed. The thigh lesion was positive for MM. The specimen obtained from the knee demonstrated a proliferation of spindle and epithelioid cells associated with focal fibrosis and scattered giant cells with brown pigment, raising the possibility of melanoma metastasis with treatment effect. Additional immunohistochemical studies with anti-SOX10 failed to demonstrate melanoma cells in the lesion. The final diagnosis for the knee nodule was pigmented villonodular synovitis. This case highlights the potential for pigmented villonodular synovitis to mimic MM, requiring additional pathologic analysis to yield an accurate diagnosis.

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Musculoskeletal Cancers

The past 25 years have seen significant growth in the role of positron emission tomography/computed tomography (PET/CT) in musculoskeletal oncology. Substantiative advances in technical capability and image quality have been paralleled by increasingly widespread clinical adoption and implementation. It is now recognized that PET/CT is useful in diagnosis, staging, prognostication, response assessment, and surveillance of bone and soft tissue sarcomas, often providing critical information in addition to conventional imaging assessment. As individualized, precision medicine continues to evolve for patients with sarcoma, PET/CT is uniquely positioned to offer additional insight into the biology and management of these tumors.

A severe headache due to pigmented villonodular synovitis in a rare location: facial nerve on temporomandibular joint. A case report

BACKGROUND

Pigmented villonodular synovitis (PVNS) is an infrequent benign tumor-like proliferative lesion developing from the synovial membranes of the joint, tendon sheath, and bursa.

CLINICAL PRESENTATION

A 44-year-old woman with numbness on the right side of her face, severe headaches, and swelling in temporomandibular region is presented. On head and neck magnetic resonance imaging, an encapsulated mass approximately 2 cm was detected. The fine-needle aspiration biopsy resulted as suspicion of mesenchymal tumor. A complete resection with the capsule was performed over the temporal branch by monitoring of the facial nerve. The final histopathologic examination resulted as a giant cell tendon sheath tumor.

CONCLUSION

Headache is not the main symptom in PVNS, but in severe pain spreading from the temporomandibular region, physical examination should be done carefully for slight swelling, and the possibility of pigmented villonodular synovitis should be considered. Because of the high recurrence rate, en bloc resection is necessary.

Imaging characteristics of tenosynovial giant cell tumors on 18F-fluorodeoxyglucose positron emission tomography/computed tomography: a retrospective observational study

BACKGROUND

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) is useful for assessing location, metastasis, staging, and recurrence of malignant tumors. Tenosynovial giant cell tumor (TSGCT) is a benign tumor; however, some studies have reported that TSGCTs have a high uptake of FDG. Few studies have reported on the detailed evaluation of TSGCT using ¹⁸F-FDG-PET/CT. The purpose of the current study is to evaluate the image characteristics and locations, particularly where possible, with or without, extra-articular invasion from TSGCT of the knee in ¹⁸F-FDG-PET/CT could occur.

METHODS

We retrospectively reviewed the patients with TSGCT who were diagnosed pathologically either by biopsy or surgical specimen. Furthermore, we evaluated the difference of the maximum standardized uptake value (SUVmax) between diffused TSGCT with extra-articular invasion and TSGCT with intra-articular localization in the knee.

RESULTS

The study consisted of 20 patients with TSGCT. The mean SUVmax of TSGCT was 12.0 ± 6.50. There were five patients with TSGCT arising in the knee with extra-articular invasion and six with TSGCT with intra-articular localization. The mean SUVmax of TSGCT with extra-articular invasion and those with intra-articular localization were 14.3 ± 6.00 and 5.94 ± 3.89, respectively. TSGCT with extra-articular invasion had significantly higher SUVmax than TSGCT with intra-articular localization (p < 0.05).

CONCLUSIONS

TSGCT revealed high FDG uptake. Furthermore, SUVmax was higher in diffused TSGCT with extra-articular invasion than in intra-articular localized TSGCT; this may reflect its local aggressiveness.

Randomized placebo-controlled double-blind phase II study of zaltoprofen for patients with diffuse-type and unresectable localized tenosynovial giant cell tumors: The REALIZE study

Background

A tenosynovial giant cell tumor (TGCT) is a locally aggressive benign neoplasm arising from intra- or extra-articular tissue, categorized as localized (L-TGCT, solitary lesion) and diffuse (D-TGCT, multiple lesions) TGCT. Surgical excision is the mainstay of the treatment, and a high local recurrence rate of approximately 50% has been reported. We focused on zaltoprofen, a nonsteroidal anti-inflammatory drug that can activate peroxisome proliferator-activated receptor gamma (PPARγ) and inhibit the proliferation of TGCT stromal cells. Therefore, we conducted a randomized trial to evaluate the safety and effectiveness of zaltoprofen in patients with D-TGCTs or unresectable L-TGCTs.

Methods

This randomized, placebo-controlled, double-blind, multicenter trial evaluated the safety and efficacy of zaltoprofen. In the treatment group, zaltoprofen (480 mg/day) was administered for 48 weeks; the placebo group received similar dosages without zaltoprofen. The primary outcome was progression-free rate (PFR) 48 weeks after treatment administration. Disease progression was defined as the following conditions requiring surgical intervention: 1) repetitive joint swelling due to hemorrhage, 2) joint range of motion limitation, 3) invasion of the adjacent cartilage or bone, 4) severe joint space narrowing, and 5) increased tumor size (target lesion).

Results

Forty-one patients were allocated to the zaltoprofen (n=21) or placebo (n=20) groups. The PFR was not significant between the zaltoprofen group and the placebo group at 48 weeks (84.0% and 90.0%, respectively; p=0.619). The mean Japanese Orthopedic Association knee score significantly improved from baseline to week 48 in the zaltoprofen group (85.38 versus 93.75, p=0.027). There was a significant difference between the values at 48 weeks of placebo and zaltoprofen group (p=0.014). One severe adverse event (grade 3 hypertension) was observed in the zaltoprofen group.

Discussion

This is the first study to evaluate the efficacy and safety of zaltoprofen in patients with TGCT. No significant differences in PFR were observed between the groups at 48 weeks. Physical function significantly improved after zaltoprofen treatment. The safety profile of zaltoprofen was acceptable. This less invasive and safer treatment with zaltoprofen, compared to surgical removal, could be justified as a novel approach to treating TGCT. Further analysis of long-term administration of zaltoprofen should be considered in future studies.

Clinical Trial Registration

University Hospital Medical Information Network Clinical Trials Registry, identifier (UMIN000025901).

FDG PET/CT in Tenosynovial Giant Cell Tumor of the Lumbar Facet Joint

ABSTRACT

Tenosynovial giant cell tumor rarely affects the facet joints of the spine. We describe FDG PET/CT findings in a case of tenosynovial giant cell tumor arising from the left L2 to L3 facet joint. The tumor caused osteolytic bone destruction of the facet joint and showed intense FDG uptake with SUVmax of 10.4. This case indicates tenosynovial giant cell tumor should be included in the differential diagnosis of abnormal facet joint FDG accumulation.

Tenosynovial giant cell tumor of the distal tibiofibular joint

Tenosynovial giant cell tumors are extremely rare tumors with highly nonspecific symptoms. This benign but aggressive disease has a slow course of progression; however, it can ultimately lead to irreversible damage to a joint. Here we describe a case of a 45-year-old female with a diagnosis of tenosynovial giant cell tumors of the distal tibiofibular joint, the second case described in the literature for such location. Appropriate imaging studies and ultimately histologic studies are necessary for the correct diagnosis. Some locations are particularly unusual for these tumors making a high level of suspicion as well as treatment by an oncology orthopedic surgery specialist at a high-volume center paramount.

Quantitative Musculoskeletal Tumor Imaging

The role of quantitative magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) techniques continues to grow and evolve in the evaluation of musculoskeletal tumors. In this review we discuss the MRI quantitative techniques of volumetric measurement, chemical shift imaging, diffusion-weighted imaging, elastography, spectroscopy, and dynamic contrast enhancement. We also review quantitative PET techniques in the evaluation of musculoskeletal tumors, as well as virtual surgical planning and three-dimensional printing.

Diffuse-type tenosynovial giant cell tumor of the temporomandibular joint with skull base invasion: a report of 22 cases with literature review

OBJECTIVES

The aim of this study was to retrospectively analyze the clinical characteristics, surgical treatment, and prognosis of patients with diffuse-type tenosynovial giant cell tumor (D-TGCT) involving the temporomandibular joint (TMJ) and the skull base.

STUDY DESIGN

A retrospective study was performed in patients with D-TGCT involving the TMJ and the skull base at our institute from April 2009 to August 2018. Data on clinical characteristics, surgical treatment, and prognosis were collected and analyzed. A literature search on D-TGCT involving the TMJ was conducted and the data analyzed.

RESULTS

The study included 22 patients (14 males and 8 females), with an average age of 44 years. The main symptoms were headache and hearing limitation, accompanied by a swelling in the TMJ area. Magnetic resonance imaging (MRI) showed low signals on T1- and T2-weighted images. All lesions were completely removed. Temporal bone flap, titanium mesh, and temporal muscle flap were used for reconstruction. The recurrence rate was 4.5%. In the literature, 115 cases were reported. Surgery alone was performed in 88 cases; postoperative radiotherapy was performed in 19 cases; the tumor recurrence rates were 9.1% and 15.8% for the 2 procedures, respectively. All patients were alive at the end of the follow-up period.

CONCLUSIONS

D-TGCT involving the TMJ and the skull base is a locally aggressive but benign lesion necessitating complete resection and has a good prognosis.

Unusual manifestations of diffuse-type tenosynovial giant cell tumor in two patients: importance of radiologic-pathologic correlation

Diffuse-type tenosynovial giant cell tumor (TSGCT) is a rare, locally aggressive neoplasm. It most commonly occurs in the knee, followed by the hip, and has distinctive imaging features, including mass-like foci of low T2 signal intensity, "blooming" on gradient-echo MRI, and pronounced uptake on FDG PET/CT. Histologically, TSGCT demonstrates a neoplastic population of mononuclear cells admixed with hemosiderin-laden macrophages, foamy histiocytes, inflammatory cells, and osteoclast-like giant cells. In cases where diffuse-type TSGCT presents in an uncommon location or with atypical features, the imaging diagnosis may be challenging. Furthermore, because of its polymorphous appearance, it may be mistaken microscopically for other neoplastic and non-neoplastic histiocytic lesions. Herein, we present two cases of diffuse-type TSGCT presenting as large masses, and underscore the importance of radiologic-pathologic correlation for accurate diagnosis.

Pigmented villous nodular synovitis mimicking metastases on 18F-FDG PET/CT in a patient with rectal mucosal melanoma: a case report

BACKGROUND

Mucosal melanomas are rare and have a high potential for metastasizing. Surgical resection is the treatment of choice for single distant metastases. Malignant melanoma usually shows the highest uptake of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG). ¹⁸F- FDG positron emission tomography /computed tomography (PET/CT) is usually used for melanoma staging. An extensive literature review revealed only 4 published case reports and an original paper involving 8 cases (12 cases in total) of patients with skin melanomas in whom pigmented villous nodular synovitis (PVNS) mimicked metastatic melanoma, however, none of the melanomas reported were of rectal mucosal origin.

CASE PRESENTATION

A 60-year-old woman presented with recent diagnosis of rectal mucosal melanoma, two additional ¹⁸F-FDG-avid lesions in the left ankle and left foot were detected on ¹⁸F-FDG PET/CT. Metastases were initially suspected; however, the final diagnosis was PVNS.

CONCLUSIONS

This is the first report of PVNS mimicking metastases on ¹⁸F-FDG PET/CT in a patient with rectal mucosal melanoma. Although high ¹⁸F-FDG-avid lesions in patients with rectal mucosal melanoma are highly suspected to be metastasis and warrant an meticulous examination, the present case is a reminder that in such patients, not all lesions with high ¹⁸F-FDG uptake, especially those near a joint, are metastases and that more extensive resection is unnecessary.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Thoracic Spine: Appearance on FDG PET/CT

D-TGCT (diffuse-type tenosynovial giant cell tumor) is a benign proliferative disorder of the synovial membranes that usually occurs in the appendicular skeleton, especially large joints such as the knee, hip, and elbow. It rarely involves the spine. In this report, we describe a rare case of D-TGCT in the thoracic spine, which showed a lytic lesion with high FDG uptake. It can mimic metastases or neurogenic tumors and should be included in the differential diagnosis of spinal tumors.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Shoulder Evaluated by FDG PET/CT

Diffuse-type tenosynovial giant cell tumor is a locally aggressive neoplasm that typically involves the knee and hip but rarely involves the shoulder. In this case, a 74-year-old woman presented a painless mass in the right shoulder. FDG PET/CT demonstrated intense FDG uptake with an SUVmax of 19.2 in the lesion. The mass was dissected and confirmed as diffuse-type tenosynovial giant cell tumor by pathology. Follow-up FDG PET/CT assessment revealed more extensive soft tissue infiltration and adjacent bone erosion 3 years after surgery. Thus, FDG PET/CT well demonstrated the hypermetabolic and local aggressive characteristics of the lesion.

Significance of incidental intra-articular and peri-articular FDG avid foci on PET/CT

BACKGROUND

Positron emission tomography/computed tomography (PET/CT) is a useful imaging adjunct in patients with sarcoma. Intra-articular and peri-articular 18F-fluoro-2-deoxy-D-glucose (FDG) avid lesions are often discovered incidentally.

PURPOSE

To describe the etiology, appearance, and standardized uptake values (SUV) of incidentally detected FDG avid intra-articular and peri-articular foci in patients with sarcoma.

MATERIAL AND METHODS

The institutional sarcoma database between November 2011 and November 2016 was retrospectively reviewed. Patients were included if a PET/CT scan was performed and an FDG avid intra-articular or peri-articular focus was found that was distinct from the primary sarcoma.

RESULTS

The majority of FDG avid foci represented benign, non-physiologic conditions such as osteoarthritis, enthesopathy, bursitis, and post-surgical changes. Six patients each had radiographic features consistent with tenosynovial giant cell tumor (TSGCT) and metastatic disease, respectively. Lower SUV, bilateral findings, and the absence of metastatic disease elsewhere were associated with benign etiologies. There was a statistically significant difference between the mean SUV measured in patients with TSGCT and those with benign, non-physiologic conditions ( P < 0.001). The difference between the benign, non-physiologic cohort and the cohort with widespread metastatic disease did not reach statistical significance ( P = 0.07).

CONCLUSIONS

In patients with soft-tissue or osseous sarcomas, isolated FDG avid intra-articular or peri-articular foci without additional metastatic lesions likely represent benign processes. Isolated intra-articular or peri-articular foci with significantly elevated SUV measurements were favored to represent TSGCT in this series.

Hot shoulder PET/CT lesion: Unusual presentation of tenosynovial giant cell tumor

We present a case of a tenosynovial giant cell tumor (TGCT) incidentally discovered at the shoulder on PET/CT, in a patient with history of thyroid cancer. Many documented cases of TGCT have been incidentally imaged by PET/CT and have been found to have varying levels of metabolic activity, however the shoulder location is unusual. This type of musculoskeletal lesion often has MRI characteristics, such as gradient echo blooming, which can render a confident diagnosis without need for biopsy.

Imaging features for diffuse-type tenosynovial giant cell tumor of the temporomandibular joint: A case report

RATIONALE

The tenosynovial giant cell tumor (TGCT) is a benign but locally aggressive tumor that arises from the synovial membrane of joints, tendon sheaths, and bursae. Although any joint can be affected, involvement of the temporomandibular joint (TMJ) was reported very rarely, and there is no relevant report on F-FDG PET/computerized tomography (CT).

PATIENT CONCERNS AND DIAGNOSES

We present here a rare case of diffuse-type of TGCT (D-TGCT) arising from the right TMJ in a 74-year-old woman. The patient was discovered a mass of the right temporal fossa during a head CT scan. However, she did not receive any treatment and was discharged from the hospital. She visited our institution again after 4 years with worsening headache and swelling of the right preauricular area. An enhanced CT demonstrated a 6.0 × 3.4 × 5.0 cm mass of mixed density involving the right TMJ, with evident enhancement and extensive erosion of adjacent bones. Magnetic resonance imaging (MRI) showed hypointensity in the solid part of the mass but high signal intensity in the cystic part or necrosis on T2-weighted images (T2WI). In F-FDG PET/CT images, the solid portion of the mass had increased FDG uptake with a SUVmax of 19.8. It was then diagnosed as D-TGCT by postoperative pathology.

LESSONS

The case report shows the imaging features of the TGCT, including CT, MRI, and F-FDG PET/CT, especially the typical hypointensity on T2WI. Careful preoperative examination and complete resection are the factors that lead to the optimal treatment of the TGCT.

Pigmented villonodular synovitis mimics metastases on fluorine 18 fluorodeoxyglucose position emission tomography-computed tomography

Pigmented villonodular synovitis (PVNS) is a benign joint disease best characterized on magnetic resonance imaging (MRI). The role of fluorine 18 fluorodeoxyglucose ((18)F-FDG) position emission tomography-computed tomography (PET-CT) in the diagnosis or characterization remains unclear. PVNS displays as a focal FDG avid lesion, which can masquerade as a metastatic lesion, on PET-CET. We present a case of PVNS found on surveillance imaging of a lymphoma patient.

Tenosynovial giant cell tumors in unusual locations detected by positron emission tomography imaging confused with malignant tumors: report of two cases

Background

A tenosynovial giant cell tumor (T-GCT) is a benign synovial tumor arising from the synovium, bursae, or tendon sheath. It can be intra- or extra-articular and localized or diffuse. Diffuse T-GCT is considered as a locally aggressive. Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose with computed tomography (FDG PET/CT) is widely used to differentiate malignant from benign tumors and to detect distant metastasis. However, FDG PET/CT is limited by false-positive findings. In this study, we present two cases of T-GCT that developed in unusual locations and were confused with malignant tumors. The final diagnoses were histologically confirmed as T-GCTs.

Case presentation

Case 1. A 45-year-old Japanese female presented with a left choroidal melanoma and an abnormal lesion adjacent to the first cervical (C1) lamina confirmed by a PET scan (maximum standardized uptake value [SUVmax] = 9.9 g/ml). MRI of the neck also detected a soft tissue mass (14.6 × 7.7 × 7 mm) adjacent to the C1 lamina. The choroidal melanoma was treated by heavy carbon ion radiotherapy. Although the size of the C1 soft tissue tumor remained unchanged, a CT-guided biopsy confirmed the diagnosis of the neck mass as a T-GCT.

Case 2. A 15-year-old Japanese male with multiple type 1 neurofibromatosis presented with a soft tissue mass (26.1 × 24.7 × 11.5 mm) of the extra-articular hip joint that was coincidentally detected by FDG PET/CT during examination of a mediastinal soft tissue mass. SUVmax of the mediastinal lesion was 2.6 g/ml and of the hip lesion was 12.8 g/ml. Thus, differentiation from a malignant tumor, such as a malignant peripheral nerve sheath tumor, was necessary. An open biopsy was performed, and the frozen section was diagnosed as T-GCT. The tumor was excised, and the final histological diagnosis confirmed T-GCT.

Conclusion

T-GCT can show high FDG uptake, which might be confused with malignancy. Although MRI findings and location might help in the diagnosis of a T-GCT, careful assessment is mandatory, especially in unusual locations.