This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 881
Topic: 10. Pathology and Oncology
A 65-year-old male presents with a large, destructive metastatic lesion in the proximal humerus. Biopsy confirms metastatic renal cell carcinoma. Before proceeding with wide resection and endoprosthetic reconstruction, what is the most critical preoperative intervention to minimize intraoperative morbidity?
Correct Answer & Explanation
. Preoperative selective arterial embolization
Explanation
Metastatic renal cell carcinoma and thyroid carcinoma lesions are notoriously hypervascular. Preoperative selective arterial embolization is critical to significantly reduce intraoperative blood loss.
Question 882
Topic: Bone Tumors
A 10-year-old girl is evaluated for precocious puberty, café-au-lait macules with irregular borders (coast of Maine), and multiple lytic bone lesions showing a "ground-glass" appearance on radiographs. What is the underlying genetic mutation responsible for this syndrome?
Correct Answer & Explanation
. GNAS1 gene mutation
Explanation
The clinical triad describes McCune-Albright syndrome, which is associated with polyostotic fibrous dysplasia. It is caused by an activating post-zygotic somatic mutation in the GNAS1 gene.
Question 883
Topic: 10. Pathology and Oncology
A 55-year-old male presents with a large soft tissue mass in the anterior compartment of his thigh. Imaging is highly suspicious for a soft tissue sarcoma. An incisional biopsy is planned. Which of the following is the most critical principle to adhere to during the biopsy?
Correct Answer & Explanation
. Ensure careful hemostasis to prevent a post-operative hematoma from contaminating adjacent planes
Explanation
Meticulous hemostasis is critical in sarcoma biopsies to prevent a hematoma from tracking and contaminating adjacent tissue planes. Incisions should be longitudinal, tourniquets may be used but without exsanguination to prevent proximal tumor spread, and tissue planes should not be widely dissected.
Question 884
Topic: 10. Pathology and Oncology
A 62-year-old female with a history of breast cancer presents with increasing right thigh pain. Radiographs reveal a 4 cm lytic lesion in the peritrochanteric region with 50% cortical destruction.
According to Mirels' criteria, what is the most appropriate management?
Correct Answer & Explanation
. Prophylactic intramedullary nailing followed by radiation therapy
Explanation
This patient has a high Mirels' score (peritrochanteric location, lytic nature, >2/3 cortical involvement, and pain), indicating a high risk for impending pathologic fracture. Prophylactic stabilization with an intramedullary nail followed by radiation therapy is the standard of care.
Question 885
Topic: 10. Pathology and Oncology
A 50-year-old man presents with dull pelvic pain. Imaging reveals a large, destructive lesion in the right ilium with stippled calcifications. Biopsy confirms a grade II chondrosarcoma. What is the most appropriate definitive management?
Correct Answer & Explanation
. Wide surgical resection alone
Explanation
Chondrosarcomas are notably resistant to both chemotherapy and radiation therapy due to their poor vascularity and slow growth rate. The mainstay of treatment for intermediate and high-grade chondrosarcomas is wide surgical excision with negative margins.
Question 886
Topic: 10. Pathology and Oncology
A 14-year-old boy trips and sustains a closed fracture of the distal femur. Initial radiographs and subsequent MRI strongly suggest a primary osteosarcoma at the fracture site. A diagnostic biopsy confirms high-grade osteosarcoma. What is the recommended treatment strategy?
Correct Answer & Explanation
. Neoadjuvant chemotherapy followed by attempted limb-salvage wide resection
Explanation
A pathologic fracture through an osteosarcoma is no longer an absolute indication for amputation. The standard of care remains neoadjuvant chemotherapy, and if the fracture callus and tumor respond well, limb-salvage surgery with wide margins can often be safely performed.
Question 887
Topic: 10. Pathology and Oncology
A 68-year-old male presents with severe right arm pain and an impending pathologic fracture of the humerus. Workup reveals a solitary, destructive lytic lesion and a new diagnosis of metastatic renal cell carcinoma.
If surgical stabilization is planned, what preoperative intervention is most critical to decrease perioperative morbidity?
Correct Answer & Explanation
. Preoperative arterial embolization of the lesion
Explanation
Metastatic renal cell carcinoma and thyroid carcinoma lesions are notoriously hypervascular and can lead to massive, life-threatening hemorrhage during surgery. Preoperative arterial embolization within 24 to 48 hours of surgery is highly recommended to significantly reduce intraoperative blood loss.
Question 888
Topic: Bone Tumors
A 65-year-old male presents with back pain, anemia, hypercalcemia, and elevated creatinine. Radiographs show multiple punched-out lytic lesions in the skull and spine. Which of the following imaging modalities is LEAST likely to accurately reflect the extent of his skeletal disease?
Correct Answer & Explanation
. Technetium-99m bone scan
Explanation
The patient's presentation is classic for multiple myeloma. Technetium-99m bone scans rely on osteoblastic activity, which is typically suppressed in myeloma lesions, frequently resulting in false-negative or cold scans.
Question 889
Topic: 10. Pathology and Oncology
A 12-year-old boy presents with a painful, swollen mid-thigh. Radiographs show a permeative diaphyseal lesion with an onion-skin periosteal reaction. A biopsy is performed. Which of the following cytogenetic abnormalities is most characteristic of this diagnosis?
Correct Answer & Explanation
. t(11;22) translocation resulting in the EWS-FLI1 fusion gene
Explanation
The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is driven by the t(11;22)(q24;q12) translocation in approximately 85% of cases, which produces the EWS-FLI1 fusion protein.
Question 890
Topic: 10. Pathology and Oncology
During a biopsy of a suspected high-grade sarcoma of the proximal tibia, the surgeon utilizes a transverse incision, elevates large fasciocutaneous flaps, and inadvertently exposes the adjacent popliteal neurovascular bundle. What is the most significant consequence of this technical error?
Correct Answer & Explanation
. It converts a potential limb-sparing wide resection into an obligatory amputation
Explanation
Biopsy tracts and any contaminated tissue planes must be excised en bloc during definitive tumor resection. A transverse incision with wide flap elevation and neurovascular contamination often makes it impossible to achieve negative margins while preserving the limb, thus necessitating amputation.
Question 891
Topic: 10. Pathology and Oncology
A 28-year-old female presents with a 6-month history of worsening knee pain and swelling. She has a known history of a giant cell tumor (GCT) of the distal femur treated with extended curettage and adjuvant phenol 3 years prior. Recent MRI reveals a recurrent lesion with significant cortical destruction, extension through the posterior cortex, and a small soft tissue component within the popliteal fossa. There is no evidence of distant metastasis. Which Enneking stage best describes this recurrent tumor?
Correct Answer & Explanation
. Stage 3 (Aggressive)
Explanation
Correct Answer: CThe Enneking staging system for benign tumors classifies them into Latent (Stage 1), Active (Stage 2), and Aggressive (Stage 3). A giant cell tumor (GCT) is a benign but locally aggressive tumor. A recurrent GCT with significant cortical destruction and extension into the soft tissue (popliteal fossa) demonstrates aggressive local behavior. These characteristics, including a high propensity for local recurrence and local tissue destruction, classify it as an Enneking Stage 3 (Aggressive) benign tumor. It is not reclassified as malignant (Stage IIA or IIB) unless there is definitive histological evidence of sarcomatous transformation, which is not stated here. Stage 1 is for asymptomatic, well-contained lesions, and Stage 2 is for symptomatic, expanding lesions still contained within bone or a natural barrier without extensive destruction.
Question 892
Topic: 10. Pathology and Oncology
A 55-year-old male presents with a rapidly growing, painful mass in his posterior thigh. Biopsy confirms a high-grade undifferentiated pleomorphic sarcoma (UPS). MRI demonstrates the tumor originating in the deep posterior compartment, with clear extension into the popliteal fossa and encasement of the popliteal artery and sciatic nerve. CT chest, abdomen, and pelvis are negative for metastasis. What is the appropriate Enneking surgical stage for this tumor?
Correct Answer & Explanation
. Stage IIB
Explanation
The Enneking Musculoskeletal Tumor Society (MSTS) staging system for malignant tumors uses histological grade (G), local extent (T), and presence of metastasis (M). High-grade malignant tumors are classified as Stage II (G2). The tumor's local extent is determined by whether it is intracompartmental (T1) or extracompartmental (T2). In this case, the UPS is high-grade (G2). Its extension into the popliteal fossa, which is an inherently extracompartmental space, and encasement of major neurovascular structures (popliteal artery and sciatic nerve) unequivocally classify it as extracompartmental (T2). With no distant metastasis (M0), this corresponds to Stage IIB (G2 T2 M0).
Question 893
Topic: 10. Pathology and Oncology
A 17-year-old male is diagnosed with a high-grade osteosarcoma of the proximal tibia. Initial staging MRI shows the tumor is confined to the proximal tibia, without cortical breach or soft tissue extension. However, a CT scan of the chest reveals multiple bilateral pulmonary nodules, confirmed as metastatic osteosarcoma on biopsy. What is the Enneking surgical stage?
Correct Answer & Explanation
. Stage III
Explanation
According to the Enneking MSTS staging system, any malignant tumor, regardless of its histological grade (G) or local extent (T), that has distant metastasis (M1) is automatically classified as Stage III. The presence of confirmed metastatic lung disease dictates this classification, overriding the local findings of a high-grade (G2) intracompartmental (T1) tumor. Stage III indicates the poorest prognosis and typically requires systemic treatment as the primary focus.
Question 894
Topic: 10. Pathology and Oncology
Which of the following anatomical locations or scenarios, when involved by a primary bone or soft tissue sarcoma, inherently classifies the tumor as extracompartmental (T2) in the Enneking system?
Correct Answer & Explanation
. A tumor in the gluteal compartment that has caused a pathological fracture
Explanation
Correct Answer: CExtracompartmental (T2) tumors are those that have extended beyond natural anatomical barriers or are located in inherently extracompartmental spaces. A pathological fracture through a malignant tumor is generally considered to have violated the tumor's natural containment, spreading tumor cells into the surrounding soft tissues and contaminating previously uninvolved compartments. Thus, it effectively converts an intracompartmental (T1) tumor to an extracompartmental (T2) tumor. The medullary canal, anterior fascial compartment of the forearm, and deep posterior compartment of the leg are all examples of well-defined intracompartmental spaces (T1) if the tumor remains confined within them. While a tumor confined to the intra-articular space of the knee joint could be argued as T2 due to the lack of strong fascial barriers, a pathological fracture definitively makes a tumor T2 by definition of violating containment.
Question 895
Topic: 10. Pathology and Oncology
A 40-year-old male presents with a suspected high-grade sarcoma of the mid-femoral diaphysis. An initial biopsy was performed by a general surgeon using a transverse incision across the anterior thigh. Subsequent staging MRI shows tumor contamination along the biopsy tract extending into the quadriceps muscle and crossing fascial planes. How does this improper biopsy technique primarily impact the Enneking surgical staging and subsequent treatment?
Correct Answer & Explanation
. It converts an intracompartmental (T1) tumor to an extracompartmental (T2) tumor, necessitating a wider resection.
Explanation
Improperly placed or performed biopsies, such as a transverse incision that contaminates adjacent compartments or neurovascular bundles, can effectively convert an intracompartmental (T1) tumor into an extracompartmental (T2) one. This 'contamination' means tumor cells have been spread beyond the original confines, necessitating a wider, more radical resection to achieve clear margins and significantly impacting surgical options and prognosis. It does not directly make the tumor ungradable, nor does it automatically lead to systemic metastasis (Stage III), prevent chemotherapy, or only affect cosmetics. The primary impact is on the local T-stage and the required surgical margin.
Question 896
Topic: 10. Pathology and Oncology
A 35-year-old patient presents with a painful, enlarging mass in the distal tibia. Plain radiographs show a lytic lesion. For precise local staging of this suspected bone sarcoma, particularly regarding its true extent within the bone marrow and its relationship to surrounding soft tissues and neurovascular structures, which imaging modality is considered the gold standard?
Correct Answer & Explanation
. Magnetic Resonance Imaging (MRI) with contrast
Explanation
Correct Answer: CMagnetic Resonance Imaging (MRI) with contrast is the gold standard for local staging of bone and soft tissue sarcomas. It provides superior soft tissue contrast, allowing for precise delineation of tumor margins, identification of neurovascular involvement, assessment of marrow extension along the medullary canal, and evaluation of fascial compartment transgressions. These details are crucial for determining the T-stage (intracompartmental vs. extracompartmental) and for meticulous surgical planning. While CT is excellent for cortical bone detail, and PET shows metabolic activity, MRI offers the best anatomical detail for local extent and soft tissue relationships. Bone scintigraphy is primarily for detecting distant bone metastases, and ultrasound has limited utility for deep bone tumors.
Question 897
Topic: 10. Pathology and Oncology
A 60-year-old male presents with acute pain and inability to bear weight after a minor fall. X-rays reveal a pathologic fracture of the proximal femur through a large lytic lesion. Biopsy confirms a high-grade osteosarcoma. Prior imaging (before the fracture) suggested the tumor was confined to the bone. Staging workup reveals no distant metastasis. How does the pathological fracture typically influence the Enneking surgical stage?
Correct Answer & Explanation
. It changes the local extent from intracompartmental (T1) to extracompartmental (T2).
Explanation
A pathological fracture through a malignant tumor is generally considered to have violated the tumor's natural containment, spreading tumor cells into the surrounding soft tissues and contaminating previously uninvolved compartments. Therefore, it effectively converts an intracompartmental (T1) tumor to an extracompartmental (T2) tumor, even if imaging prior to fracture suggested T1. This increases the local recurrence risk and necessitates a wider margin of resection. It does not automatically imply metastasis (Stage III) or change the histological grade. While it significantly impacts treatment, it specifically alters the T-stage component of the Enneking system.
Question 898
Topic: 10. Pathology and Oncology
A 20-year-old patient with a high-grade osteosarcoma of the distal femur undergoes comprehensive staging. MRI shows the primary tumor confined to the distal femur. However, a whole-body bone scan reveals a separate, discontinuous focus of increased uptake in the ipsilateral proximal tibia, confirmed as osteosarcoma on biopsy. There are no other distant metastases (e.g., lungs, lymph nodes). How is this finding typically interpreted for Enneking surgical staging?
Correct Answer & Explanation
. It automatically upstages the tumor to Stage III.
Explanation
A skip lesion is a discontinuous focus of tumor within the same bone or in an adjacent bone within the same extremity, occurring without direct extension. In the Enneking system, the presence of a skip lesion is considered a form of regional metastasis (M1) and automatically upstages the tumor to Stage III, as it implies a much higher risk of systemic disease, even if distant metastases are not yet evident in other organs. This is a critical point for determining prognosis and treatment, as it indicates a more advanced disease state than a localized Stage IIB tumor.
Question 899
Topic: 10. Pathology and Oncology
A 48-year-old female presents with a 6 cm, slowly growing, deep-seated soft tissue mass in her anterior thigh. Biopsy reveals a low-grade myxofibrosarcoma. MRI shows the tumor is entirely confined within the anterior fascial compartment, without involvement of the femoral neurovascular bundle or cortical bone. No regional lymph node or distant metastases are identified. What is the Enneking surgical stage for this tumor?
Correct Answer & Explanation
. Stage IA
Explanation
This patient has a low-grade (G1) malignant tumor (myxofibrosarcoma). The MRI confirms that the tumor is entirely confined within the anterior fascial compartment of the thigh, which is considered an intracompartmental (T1) space. There is no evidence of regional lymph node or distant metastasis (M0). Therefore, a low-grade (G1) intracompartmental (T1) tumor with no metastasis is classified as Enneking Stage IA. The size of the tumor (6 cm) is a factor in AJCC TNM staging but not the primary determinant for Enneking T-stage (which focuses on compartment integrity).
Question 900
Topic: 10. Pathology and Oncology
A 15-year-old male with a high-grade osteosarcoma of the distal femur undergoes neoadjuvant chemotherapy. After completion of chemotherapy, the resected specimen shows 95% tumor necrosis. While this is a critical prognostic indicator, how does this finding impact the *initial* Enneking surgical staging?
Correct Answer & Explanation
. It is a critical prognostic factor, influencing adjuvant therapy, but does not alter the initial Enneking surgical stage.
Explanation
Correct Answer: BThe percentage of tumor necrosis observed in the resected specimen after neoadjuvant chemotherapy is a crucial prognostic indicator for osteosarcoma (often termed 'response to chemotherapy'). A good response (e.g., >90% necrosis) is associated with better long-term survival and often guides decisions regarding the intensity or duration of adjuvant chemotherapy. However, this is a post-treatment pathological finding and does not alter theinitialEnneking surgical stage, which is determined pre-treatment based on the tumor's histological grade, local extent, and presence of metastasis at the time of diagnosis. The initial stage remains the same, but the response to chemotherapy provides vital prognostic information for subsequent management.
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