This practice set contains high-yield board review questions covering key concepts in Soft Tissue Tumors & Metastasis. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 1
Topic: Soft Tissue Tumors & Metastasis
A 35-year-old man presents with progressive back pain and lower extremity paresthesias. MRI demonstrates an enhancing intramedullary nodule with a large associated cyst. He also has a history of retinal angiomas. Which of the following genetic syndromes is most closely associated with this patient's spinal lesion?
Correct Answer & Explanation
. Von Hippel-Lindau disease
Explanation
The patient's presentation suggests a spinal hemangioblastoma, characterized by an enhancing mural nodule and an associated cyst. Hemangioblastomas are a hallmark of Von Hippel-Lindau (VHL) disease, which also presents with retinal angiomas and renal cell carcinomas.
Question 2
Topic: Soft Tissue Tumors & Metastasis
A 40-year-old man presents with radicular pain. MRI reveals an intradural, extramedullary mass extending through the neural foramen into the extraspinal space, creating a "dumbbell" shape. Histology shows Antoni A and Antoni B tissue patterns. The correct diagnosis is:
Correct Answer & Explanation
. Schwannoma
Explanation
Schwannomas frequently present as dumbbell-shaped tumors extending through the neural foramen. Histologically, they feature hypercellular Antoni A areas with Verocay bodies and hypocellular Antoni B areas.
Question 3
Topic: Soft Tissue Tumors & Metastasis
Which of the following histologic findings is most characteristic of a spinal schwannoma?
Correct Answer & Explanation
. Antoni A and Antoni B tissue patterns
Explanation
Schwannomas are characterized histologically by alternating regions of high cellularity (Antoni A) containing Verocay bodies, and low cellularity (Antoni B). Psammoma bodies are seen in meningiomas, and perivascular pseudorosettes in ependymomas.
Question 4
Topic: Soft Tissue Tumors & Metastasis
Which of the following genetic syndromes is most strongly associated with the development of multiple spinal hemangioblastomas?
Correct Answer & Explanation
. Von Hippel-Lindau disease
Explanation
Von Hippel-Lindau (VHL) disease is an autosomal dominant condition characterized by the formation of multiple hemangioblastomas in the central nervous system, including the brain and spinal cord, as well as renal cell carcinomas.
Question 5
Topic: Soft Tissue Tumors & Metastasis
A 10-year-old girl with Neurofibromatosis type 1 presents with a sharp, angular thoracic kyphoscoliosis (dystrophic curve) and progressive weakness in her hands. MRI shows a solid mass compressing the spinal cord at the apex of the curve. What is the most likely composition of the mass?
Correct Answer & Explanation
. Neurofibroma
Explanation
In NF-1, sharp, dystrophic kyphoscoliotic curves can be complicated by intraspinal pathology. The most common cause of cord compression in this specific scenario is an enlarging neurofibroma or severe angular deformity.
Question 6
Topic: Soft Tissue Tumors & Metastasis
This patient has numerous (> 6) café au lait spots. Which of the following describes the correct inheritance pattern?
Correct Answer & Explanation
. Autosomal dominant with high degree of penetrance
Explanation
Neurofibromatosis is an autosomal dominant condition that occurs in a peripheral and central form. The peripheral type is more common and called neurofibromatosis 1 (NF1). The central type is characterized by bilateral acoustic neurofibromatosis (NF2). The clinical presentation is variable. Patients may either have a severe form of NF1 with hundreds of neurofibromas in the skin or they may have only café au lait spots and deep neurofibromas that are easily apparent. Demographics of NF1 include: 1. Autosomal dominant with high degree of penetrance 2. Chromosomal abnormality - 17, NF1 gene (encodes neurofibromin) 3. Diagnostic criteria - two or more of the following: Six or more café au lait spots, two or more neurofibromas of any type or one plexiform neurofibroma, freckling in the axillary or inguinal area, optic glioma, two or more Lisch nodules, bone lesion, first-degree relative with NF1.
Question 7
Topic: Soft Tissue Tumors & Metastasis
Adolescent girls with multiple radiographs for idiopathic scoliosis are statistically at increased risk for which of the following problems later in life:
Correct Answer & Explanation
. Breast cancer
Explanation
In a historical cohort study, the risk was increased to 1.7 times the expected rate of breast cancer. The radiation dose is currently lower. The exposure to the breast may be lowered by taking posteroanterior rather than anteroposterior films, and eliminating lateral films in routine situations.
Question 8
Topic: Soft Tissue Tumors & Metastasis
Criteria for diagnosis of neurofibromatosis 1 (NF1) include all the signs below except:
Correct Answer & Explanation
. Neurologic deficit
Explanation
While neurologic deficit may be associated with some of the spinal deformities in neurofibromatosis 1 (NF1), it does not constitute one of the diagnostic criteria. The diagnostic criteria for NF1 were established by The C onsensus Development Conference on Neurofibromatosis at the National Institutes of Health in 1987: Six or more cafa-au-lait spots, at least 15 mm in diameter in adults and 5 mm in children. Two or more neurofibromas of any type or one plexiform neurofibroma. Freckling in the axillae or inguinal regions (Crowe sign). Two or more iris hamartomas (Lisch nodules). A distinctive osseous lesion, such as sphenoid dysplasia or thinning of long bone cortex, with or without pseudarthrosis. A first-degree relative with NF1 by the above criteria.
Question 9
Topic: Soft Tissue Tumors & Metastasis
The origin of "dumbbell lesions" found in radiographs of patients with neurofibromatosis 1 (NF1) is:
Correct Answer & Explanation
. Neurofibromas or meningoceles that protrude through spinal foramina
Explanation
Intraspinal lesions, such as neurofibromas and meningoceles, that protrude through the neural foramina give the radiologic appearance of a "dumbbell lesion." Flattening of the intervertebral disk with enlargement of the lateral borders is not a feature of neurofibromatosis 1 (NF1). Tibial dysplasia seen in patients with NF1 lead to anterolateral bowing and does not give the appearance of a dumbbell. While subperiostial bone proliferation is seen in NF1, it does not give the appearance of a dumbbell. Bone cysts are a recognized complication of NF1, but are not the origin of the dumbbell lesions seen on radiographs.
Question 10
Topic: Soft Tissue Tumors & Metastasis
Schwannomas are differentiated from neurofibromas by all of the following except:
Correct Answer & Explanation
. Presence of schwann cells
Explanation
Schwann cells contribute to schwannoma and neurofibroma.
Question 11
Topic: Soft Tissue Tumors & Metastasis
A biopsy of a deep soft tissue mass in the thigh reveals a proliferation of primitive round and spindle cells within an abundant myxoid stroma. A delicate plexiform capillary network is noted, and univacuolated lipoblasts are present. These histological features are most characteristic of which liposarcoma subtype?
Correct Answer & Explanation
. Myxoid liposarcoma
Explanation
Correct Answer: CAcademic Rationale:The description of a prominent myxoid matrix, a distinctive delicate plexiform capillary network (often described as curvilinear vessels), and a proliferation of small, primitive round and spindle cells, along with the presence of lipoblasts, are the classic histological hallmarks ofmyxoid liposarcoma. Well-differentiated liposarcoma consists primarily of mature adipocytes with atypical stromal cells. Dedifferentiated liposarcoma has a high-grade non-lipogenic component. Pleomorphic liposarcoma is characterized by marked cellular pleomorphism and bizarre giant cells. Spindle cell lipoma is a benign entity with mature adipocytes and uniform spindle cells, lacking the myxoid stroma and plexiform vascularity of myxoid liposarcoma.
Question 12
Topic: Soft Tissue Tumors & Metastasis
Which subtype of liposarcoma is particularly known for its high radiosensitivity, making radiation therapy a crucial component of its multidisciplinary management?
Correct Answer & Explanation
. Myxoid liposarcoma
Explanation
Correct Answer: CAcademic Rationale:Myxoid liposarcomais uniquely recognized among soft tissue sarcomas for its relative sensitivity to both chemotherapy and, more notably, radiation therapy. This characteristic makes radiotherapy a crucial component of its management, often utilized in neoadjuvant (pre-operative) or adjuvant (post-operative) settings to improve local control and facilitate limb salvage. While radiation therapy is used for other high-grade sarcomas, myxoid liposarcoma shows a particularly favorable response. Well-differentiated liposarcoma is less radiosensitive, and while dedifferentiated and pleomorphic liposarcomas are high-grade, myxoid liposarcoma stands out for its specific radiosensitivity.
Question 13
Topic: Soft Tissue Tumors & Metastasis
A 65-year-old man presents with a pathologic fracture of the proximal humerus. Workup reveals a solitary, highly destructive lytic lesion and a primary renal cell carcinoma. Prior to surgical fixation and curettage, what is the most appropriate next step?
Correct Answer & Explanation
. Preoperative selective arterial embolization
Explanation
Renal cell carcinoma and thyroid carcinoma metastases are notoriously hypervascular. Preoperative selective arterial embolization is recommended 24-48 hours before surgery to dramatically reduce intraoperative blood loss.
Question 14
Topic: Soft Tissue Tumors & Metastasis
A 45-year-old male is diagnosed with a massive deep myxoid liposarcoma of the thigh. Staging chest CT is negative. Which additional imaging study is uniquely critical for complete staging of this specific histologic subtype?
Correct Answer & Explanation
. MRI of the total spine
Explanation
Myxoid liposarcoma has a unique propensity for extrapulmonary metastases, particularly to the spine and other bone marrow sites. An MRI of the total spine (or whole-body MRI) is recommended for accurate staging.
Question 15
Topic: Soft Tissue Tumors & Metastasis
Following initial evaluation, an MRI of the right thigh was performed. The image below shows an axial T1-weighted view of the mass. Based on the provided image and the detailed MRI description in the case, which of the following is the most accurate interpretation of the findings?
Correct Answer & Explanation
. C. A biphasic mass with macroscopic fat (high T1 signal) and distinct nodular, non-fatty components (isointense to muscle on T1), indicative of a dedifferentiated liposarcoma.
Explanation
Correct Answer: CThe case explicitly describes the MRI findings: 'The majority of the tumor exhibited high signal intensity on T1-weighted images that suppressed on STIR sequences, confirming the presence of macroscopic adipose tissue. However, unlike a simple benign lipoma, the mass demonstrated significant heterogeneity. There were thickened, irregular internal septations (>2 mm) and distinct nodular areas of non-fatty tissue that were isointense to muscle on T1, hyperintense on T2, and demonstrated avid, heterogeneous enhancement following gadolinium administration.' This biphasic appearance, with both fatty and solid enhancing components, is the classic radiological hallmark of an atypical lipomatous tumor or a dedifferentiated liposarcoma.Option A (A homogeneous mass with low signal intensity on T1, consistent with a myxoid liposarcoma): Myxoid liposarcomas typically lack macroscopic fat on T1 and show very high signal on T2 due to the myxoid matrix, often appearing cyst-like. This does not match the description of high T1 signal from fat.Option B (A predominantly fatty mass with thin septations (<2mm) and no enhancing non-fatty components, typical of a simple lipoma): While the mass is predominantly fatty, the description of 'thickened, irregular internal septations (>2 mm) and distinct nodular areas of non-fatty tissue that... demonstrated avid, heterogeneous enhancement' rules out a simple lipoma, which would have thin septations and no significant enhancing non-fatty components.Option D (A highly heterogeneous mass with significant necrosis and hemorrhage, lacking macroscopic fat, characteristic of a pleomorphic liposarcoma): Pleomorphic liposarcomas are typically high-grade, highly heterogeneous, and often lack visible macroscopic fat on MRI. While the mass is heterogeneous, the presence of significant macroscopic fat on T1 makes pleomorphic liposarcoma less likely as the primary radiological diagnosis.Option E (A mass with serpiginous vascular channels and phleboliths, suggestive of an intramuscular hemangioma): The MRI description does not mention serpiginous vascular channels or phleboliths (signal voids), which are characteristic of hemangiomas. Plain films also did not identify phleboliths.
Question 16
Topic: Soft Tissue Tumors & Metastasis
Based on the clinical presentation, physical examination, and the MRI findings (including the image provided), which of the following diagnoses is most consistent with Mr. J.A.'s tumor?
Correct Answer & Explanation
. C. Dedifferentiated Liposarcoma
Explanation
Correct Answer: CThe clinical and radiological findings are most consistent with aDedifferentiated Liposarcoma. The case explicitly states: 'The presence of a predominantly fatty tumor with thick septations and nodular, enhancing, non-lipomatous components is the classic radiological hallmark of an atypical lipomatous tumor or a dedifferentiated liposarcoma.' The table in the case further reinforces this, describing DDLPS as having a 'Biphasic appearance. Fatty regions adjacent to prominent, solid, non-fatty, avidly enhancing nodular components.'Option A (Simple Lipoma): A simple lipoma would be homogeneously fatty with thin septations (<2mm) and no nodular enhancement. This contradicts the MRI findings of thickened septations and enhancing non-fatty nodules.Option B (Myxoid Liposarcoma): Myxoid liposarcomas typically lack macroscopic fat on T1 and show very high T2 signal due to the myxoid matrix. The MRI here clearly shows macroscopic fat (high T1 signal).Option D (Intramuscular Hemangioma): Hemangiomas can be heterogeneous but are characterized by serpiginous vascular channels and often phleboliths (signal voids), which were not described in this case's MRI or plain films.Option E (Pleomorphic Liposarcoma): Pleomorphic liposarcomas are high-grade and typically lack visible macroscopic fat on MRI, presenting as highly heterogeneous, necrotic, and hemorrhagic masses. While this tumor has high-grade features, the prominent macroscopic fat on T1 makes pleomorphic liposarcoma less likely than dedifferentiated liposarcoma, which specifically arises from a fatty precursor.
Question 17
Topic: Soft Tissue Tumors & Metastasis
A 35-year-old female presents with recurrent, spontaneous hemorrhagic effusions of her right knee. MRI reveals nodular synovial thickening with low signal intensity on both T1- and T2-weighted images, along with significant "blooming" artifact on gradient-echo sequences. What is the most likely diagnosis?
Correct Answer & Explanation
. Pigmented villonodular synovitis (PVNS)
Explanation
PVNS is characterized by hemosiderin deposition within the synovium, which causes low signal on T1/T2 and a characteristic "blooming" artifact on gradient-echo (T2*) MRI. Spontaneous hemarthrosis in a young adult is a hallmark clinical presentation.
Question 18
Topic: Soft Tissue Tumors & Metastasis
Well-differentiated liposarcomas never have chromosomal abnormalities. Liposarcomas account for approximately 10% to 15% of sarcomas. Some general statements about liposarcomas are listed below:
Correct Answer & Explanation
. Most liposarcomas occur below the fascia.
Explanation
Which of the following soft tissue lesions has a characteristic reciprocal transformation between chromosomes 12 and 16:
Question 19
Topic: Soft Tissue Tumors & Metastasis
Figures 34a through 34c show an axial proton density (spin echo long TR, short TE) image, a sagittal inversion recovery (STIR) image, and a sagittal T1-weighted (short TR, short TE) image of the left thigh. What is the most likely diagnosis?
Correct Answer & Explanation
. Hematoma
Explanation
DISCUSSION: The images reveal a region of increased signal within the rectus femoris muscle with mild, ill-defined surrounding edema. The presence of high intensity signal on the T1-weighted image favors acute blood, in this case associated with a rectus femoris muscle tear or fatty tissue. However, because of fat suppression, a fatty lesion or lipoma would be dark on STIR, rather than bright as in this image. Most foreign bodies are low intensity signal and if small, are difficult to evaluate with MRI. The lack of adjacent subcutaneous soft-tissue edema or surrounding fluid makes pyomyositis an unlikely diagnosis.REFERENCE: El-Khoury G: MRI of the Musculoskeletal System. Philadelphia, PA, JB Lippincott, 1998, p 123.
Question 20
Topic: Soft Tissue Tumors & Metastasis
Examination of the shoulder seen in Figure 52 shows atrophy and tenderness of the infraspinous fossa and profound weakness in external rotation. The supraspinous fossa shows normal muscle bulk. What is the most likely cause of this condition?
Correct Answer & Explanation
. Ganglion cyst of the spinoglenoid notch
Explanation
DISCUSSION: Compression of the suprascapular nerve by a ganglion cyst is a well-documented cause of pain and weakness in the shoulder. Isolated involvement of the infraspinatus indicates that the area of entrapment is at the spinoglenoid notch and not the suprascapular notch. The majority of ganglion cysts found in the shoulder are related to tears of the labrum. When such a compressive lesion is found, decompression can be accomplished through either an open or arthroscopic approach. Several authors have shown the value of arthroscopy in the treatment of this condition. It has been shown that it is technically possible to decompress a paralabral ganglion cyst using arthroscopy; this method is usually followed by repair of the torn labrum. Alternatively, arthroscopic repair of the labrum can be performed and the cyst may be aspirated at the time of surgery. Open cyst excision through a posterior approach is also an acceptable method of treatment.REFERENCES: Schickendantz MS, Ho CP: Suprascapular nerve compression by a ganglion cyst: Diagnosis by magnetic resonance imaging. J Shoulder Elbow Surg 1993;2:110-114.Thompson RC, Schneider W, Kennedy T: Entrapment neuropathy of the inferior branch of the suprascapular nerve by ganglia. Clin Orthop 1982;166:185-187.Iannotti JP, Ramsey ML: Arthroscopic decompression of a ganglion cyst causing suprascapular nerve compression. Arthroscopy 1996;12:739-745.
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