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Dr Mohammed Hutaif
Dr Mohammed Hutaif
العربية

ORTHOPEDIC MCQS ONLINE PATHOLOGY 017

Orthopedics MCQ online
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ORTHOPEDIC MCQS ONLINE PATHOLOGY 017

 

MUSCULOSKELETAL TUMORS AND

DISEASES SELF-SCORED SELF-ASSESSMENT EXAMINATION

AAOS 2017

 

 

CLINICAL SITUATION FOR QUESTIONS 1 THROUGH 4

Figures 1a through 1d are the MR images and biopsy specimen of a 68-year-old man who has a painless mass in his leg. He believes the mass may have been present for several years, and it is more apparent now because he recently lost weight after changing his diet and exercise patterns. He also recently experienced modest trauma to his leg while moving furniture.

 

 

 

Question 1 of 100

What is the diagnosis?

  1. Dedifferentiated liposarcoma

  2. Intramuscular lipoma

  3. Atypical lipomatous tumor

  4. Myositis ossificans

 

PREFERRED RESPONSE: 1- Dedifferentiated liposarcoma

 

Question 2 of 100

The role of surgery in this condition is best described as

  1. marginal resection is performed with a low likelihood of recurrence.

  2. best performed after the lesion becomes “cold” on a bone scan.

  3. wide resection as an indication for curative treatment.

  4. not indicated.

 

PREFERRED RESPONSE: 3- wide resection as an indication for curative treatment.

 

Question 3 of 100

The role of radiation treatment for this lesion is

  1. proven to decrease local recurrence.

  2. associated with a high rate of post-radiation sarcoma development.

  3. contra-indicated for benign pathology.

  4. associated with a higher risk of wound complications if given post-operatively.

 

PREFERRED RESPONSE: 1- proven to decrease local recurrence.

 

Question 4 of 100

Chemotherapy for this condition is

  1. contraindicated when pathology is benign.

  2. associated with a high risk for subsequent myelodysplastic syndrome.

  3. provides dramatic survival benefits.

  4. provides modest survival benefits.

 

PREFERRED RESPONSE: 4- provides modest survival benefits.

DISCUSSION

This patient has a dedifferentiated liposarcoma within a preexisting atypical lipomatous tumor. The imaging demonstrates a large fatty mass with increased internal septations proximally (the atypical lipomatous tumor) and a solid enhancing mass distally (the dedifferentiated portion). A biopsy reveals a high-grade liposarcoma. The other diagnostic responses do not reflect sarcomatous transformation of the lesion.

Surgical treatment of a high-grade sarcoma involves wide surgical resection. Radiation decreases local recurrence but does not clearly influence overall survival. The role of chemotherapy in high-grade soft-tissue sarcomas remains investigational; there is a modest (8%-15%) associated improvement in overall survival.

Intramuscular lipomas and atypical lipomatous tumors are treated with marginal resection alone. Radiation therapy for soft-tissue sarcomas may be given before or after surgery. When administered before surgery, patients have a higher wound complication rate but better long-term function attributable to lower rates of lymphedema, fibrosis, and contractures.

RECOMMENDED READINGS

J. Is PET-CT an accurate method for the differential diagnosis between chondroma and chondrosarcoma? Springerplus. 2016 Feb 29;5:236. doi: 10.1186/s40064-016-1782-8. eCollection 2016. PubMed PMID: 27026930. View Abstract at PubMed

 

CLINICAL SITUATION FOR QUESTIONS 18 THROUGH 21

Figures 18a through 18c are the radiographs and bone scan of a 23-year-old woman.

 

 

 

Question 18 of 100

What is the most likely diagnosis?

  1. Fibrous dysplasia

  2. Metastatic carcinoma

  3. Multiple hereditary exostosis

  4. Multiple myeloma

 

PREFERRED RESPONSE: 1- Fibrous dysplasia

 

Question 19 of 100

Despite adequate medical management, the patient continues to experience leg pain that interferes with even the lowest demands of daily living. You recommend prophylactic intramedullary nailing of the tibia with interlocking screws. Prior to the surgery, you should recommend

  1. an echocardiogram.

  2. an endocrinology consultation.

  3. a serum calcium level.

  4. a repeat nuclear bone scan.

 

PREFERRED RESPONSE: 2- an endocrinology consultation.

 

Question 20 of 100

The most common extraskeletal manifestation of this disease is

  1. café au lait macules.

  2. urinary protein elevation.

  3. a primary lung mass.

  4. an arrhythmia.

 

PREFERRED RESPONSE: 1- café au lait macules.

 

Question 21 of 100

The underlying cause of the neoplasm is

  1. ALK gene rearrangement.

  2. a nongerm-cell mutation of the GNAS1 gene.

  3. a germline alteration in EXT1 and EXT2.

  4. an abnormality arising from the translocation t(11;14)(q13;q32).

PREFERRED RESPONSE: 2- a nongerm-cell mutation of the GNAS1 gene.

DISCUSSION

The bone scan reveals multiple bone lesions, which does not rule out any of the responses. The radiographs reveal dysplastic bone with a “ground glass” appearance, suggesting fibrous dysplasia as the preferred response. Multiple myeloma typically demonstrates purely lytic, “punched out” lesions and would be highly unusual in a 23-year-old woman. Multiple hereditary exostosis would demonstrate more expansile lesions concentrated in the metaphysis. Metastatic carcinoma could have a lytic or blastic appearance but is less likely to occur in a 23-year-old woman.

McCune-Albright syndrome in polyostotic fibrous dysplasia is present in as many as 50% of patients and should be evaluated for during an endocrine consultation. Adrenal, pituitary, parathyroid, and thyroid endocrinopathies may be present. Untreated hyperthyroidism can be life threatening during a surgical procedure. There is no indication to repeat the nuclear bone scan. Although phosphate wasting and, rarely, oncogenic osteomalacia have been reported in polyostotic fibrous dysplasia, an endocrinology consultation always should be sought.

Café au lait macules are the most common extraskeletal manifestation of fibrous dysplasia, often referred to as “coast of Maine” in appearance because of their irregular borders (in comparison to the “Coast of California” with smooth borders as seen in neurofibromatosis). Multiple myeloma would not ordinarily appear with increased uptake on a bone scan unless a pathologic fracture of some duration were present. A long area of bone involvement would not appear in patients with metastatic lung adenocarcinoma.

An ALK rearrangement occurs in nonsmall-cell lung cancer. The translocation t(11;14)(q13;q32) should be recognized as a poor prognosticator in multiple myeloma. The germline alteration in EXT1 and EXT2 occurs in multiple hereditary exostosis.

All forms of fibrous dysplasia are caused by a nongerm-cell mutation that occurs during early embryogenesis. A missense mutation of the GNAS1 gene, which encodes the alpha subunit of the stimulatory G-protein-couple-receptor, Gs alpha, results in G-protein activation and the production of cyclic adenosine monophosphate affecting melanocytes, endocrine cells, and osteoprogenitor cells.

RECOMMENDED READINGS

 

RESPONSES FOR QUESTIONS 26 THROUGH 31

  1. Ultrasound

  2. MRI with and without contrast

  3. Chest CT scan and whole-body bone scan

  4. Positron emission tomography (PET)

  5. Presurgical radiation therapy

  6. Marginal resection

  7. Transverse incisional biopsy centered over the mass

  8. Incisional biopsy centered over the mass in line with the long axis of the limb

  9. Sentinel node biopsy

  10. Core needle biopsy

For each clinical scenario or question below, select the most appropriate evaluation or treatment step listed above.

 

Question 26 of 100

Figure 26 is the posteroranterior chest radiograph of a 76-year-old man with an atraumatic gradually enlarging mass overlying his left clavicle that has been present for 6 months. There are no changes in overlying skin. His only noteworthy medical history involves facial squamous cell carcinomas that have been successfully removed surgically.

  1. Ultrasound

  2. MRI with and without contrast

  3. Chest CT scan and whole-body bone scan

  4. Positron emission tomography (PET)

  5. Presurgical radiation therapy

  6. Marginal resection

  7. Transverse incisional biopsy centered over the mass

  8. Incisional biopsy centered over the mass in line with the long axis of the limb

  9. Sentinel node biopsy

  10. Core needle biopsy

 

 

 

 

PREFERRED RESPONSE: 2- MRI with and without contrast

 

Question 27 of 100

A 63-year-old man with right hip pain was followed 8 years ago for an incidental intraosseous lesion in the right periacetabular and ischial region that was isointense with fat on all images. He was discharged from follow-up after 3 years when no change was documented. He began experiencing pain in his hip, and a bone scan showed grade 3 uptake. New MR imaging was obtained, and an axial image at the level of the hip is shown in Figure 27. A PET/CT scan shows dramatic activity in the lesion without any other area of activity.

 

 

 

  1. Ultrasound

  2. MRI with and without contrast

  3. Chest CT scan and whole-body bone scan

  4. Positron emission tomography (PET)

  5. Presurgical radiation therapy

  6. Marginal resection

  7. Transverse incisional biopsy centered over the mass

  8. Incisional biopsy centered over the mass in line with the long axis of the limb

  9. Sentinel node biopsy

  10. Core needle biopsy

 

PREFERRED RESPONSE: 10- Core needle biopsy

 

Question 28 of 100

Figure 28 is the MR image of a 65-year-old man with an American Joint Committee on Cancer III anterior arm pleomorphic intermediate- to high-grade sarcoma. The patient is now considering treatment options. He underwent a wide excision at an outside hospital 2 years previously. The treating surgeon recommended an amputation, and the patient is now seeking a second opinion. Imaging studies reveal no other sites of disease.

 

 

 

  1. Ultrasound

  2. MRI with and without contrast

  3. Chest CT scan and whole-body bone scan

  4. Positron emission tomography (PET)

  5. Presurgical radiation therapy

  6. Marginal resection

  7. Transverse incisional biopsy centered over the mass

  8. Incisional biopsy centered over the mass in line with the long axis of the limb

  9. Sentinel node biopsy

  10. Core needle biopsy

PREFERRED RESPONSE: 5- Presurgical radiation therapy

 

Question 29 of 100

Figure 29 is the MR image of a 44-year-old woman who elects surgical treatment of an intramuscular lipoma in her dominant right arm.

 

 

 

  1. Ultrasound

  2. MRI with and without contrast

  3. Chest CT scan and whole-body bone scan

  4. Positron emission tomography (PET)

  5. Presurgical radiation therapy

  6. Marginal resection

  7. Transverse incisional biopsy centered over the mass

  8. Incisional biopsy centered over the mass in line with the long axis of the limb

  9. Sentinel node biopsy

  10. Core needle biopsy

 

PREFERRED RESPONSE: 6- Marginal resection

 

Question 30 of 100

Figure 30 is the MR image of a 29-year-old man with a large and enlarging thigh mass. Needle biopsy findings are inconclusive.

  1. Marginal resection

  2. Transverse incisional biopsy centered over the mass

  3. Incisional biopsy centered over the mass in line with the long axis of the limb

  4. Sentinel node biopsy

  5. Core needle biopsy

 

 

 

 

PREFERRED RESPONSE: 8- Incisional biopsy centered over the mass in line with the long axis of the limb

 

Question 31 of 100

Figure 31 is the sagittal MR image of a 30-year-old man with a clear-cell sarcoma of the foot. There is no evidence of disease elsewhere after standard staging of a soft-tissue sarcoma.

 

 

 

  1. Marginal resection

  2. Transverse incisional biopsy centered over the mass

  3. Incisional biopsy centered over the mass in line with the long axis of the limb

  4. Sentinel node biopsy

  5. Core needle biopsy

 

PREFERRED RESPONSE: 9- Sentinel node biopsy

DISCUSSION

For patients with rapidly enlarging painless masses, particularly those that are either large or deep, the diagnosis of a soft-tissue sarcoma should be entertained. Masses exceeding 5 cm in largest dimension that are subfascial and heterogenous on MRI are concerning. MRI with and without contrast is the preferred imaging modality for evaluation of soft-tissue sarcomas because it can delineate location of the lesion, involvement of neurovascular structures, intra-articular involvement, and underlying signal alteration in the osseous structures. Most patients can relate the onset of their symptoms to a traumatic event, and the interpretation of an MRI may include a hematoma. Ultrasound is more commonly used to confirm the clinical impression of a cyst and to distinguish cystic from solid masses.

A core needle biopsy can easily be performed in an outpatient setting or with image guidance to aid in the diagnosis. Core needle biopsies preserve the architectural relationship of cells, which is important in the diagnosis of mesenchymal lesions. A core needle biopsy is appropriate for soft-tissue lesions and osseous lesions and should be performed in a multidisciplinary setting with a surgeon performing the resection so unnecessary compartmental contamination is not introduced into the needle tract.

A fine-needle aspiration allows cytologic but not histologic analysis and generally is not favored for the diagnosis of a sarcoma. If an open biopsy is performed, the incision must be oriented in line with the long axis of the extremity to minimize contamination of surrounding structures. Meticulous hemostasis and closure of the tumor pseudocapsule must be achieved to minimize local tissue contamination. An open biopsy is commonly used if an initial needle biopsy is nondiagnostic. Transverse biopsy incisions should not be used.

Presurgical radiation for sarcomas is advantageous to decrease the field of radiation and overall radiation dose, but a significant postsurgical wound-healing complication rate (up to 35%) is associated with presurgical radiation therapy.

Staging of sarcomas is important to help predict prognosis. Not all sarcomas are reliably positive on a PET scan, so the preferred staging studies are CT scan of the chest and whole-body bone scan. Hematogenous spread of sarcomas is the most common route of metastatic disease, which speaks to the value of chest CT scans. Clear-cell sarcomas (in addition to synovial sarcoma, angiosarcoma, epithelioid sarcoma, and rhabdomyosarcoma) tend to involve lymphatic nodal metastatic disease, so sentinel node biopsy is considered when assessing these tumors. Evidence supports efficacy of sentinel node biopsy for clear-cell sarcomas in particular.

RECOMMENDED READINGS

CLINICAL SITUATION FOR QUESTIONS 35 THROUGH 37

Figure 35 is the intraoperative finding of a 28-year-old man with a recurrent nontraumatic effusion who undergoes arthroscopy.

 

 

 

Question 35 of 100

A neoplasm that involves rearrangements of 1p13 involving the colony-stimulating factor 1 (CSF1) gene which, when expressed, causes proliferation of neoplastic cells and the recruitment of monocyte-macrophage non-neoplastic cells is

  1. a tenosynovial giant-cell tumor.

  2. a nodular fasciitis.

  3. an infantile fibrosarcoma.

  4. an inflammatory myofibroblastic tumor.

 

PREFERRED RESPONSE: 1- a tenosynovial giant-cell tumor.

 

Question 36 of 100

This tumor has been recently treated in phase 1 trials with molecularly targeted therapies including a conformation-specific inhibitor of CSF1 receptor (CSF1R), resulting in at least a 50% reduction of tumor volume in some patients. This type of inhibitor is further defined as

  1. a tyrosine kinase inhibitor.

  2. a substrate binding synthetic molecule.

  3. an anti-CSF1R antibody.

  4. an anti-CSF1 antibody

 

PREFERRED RESPONSE: 2- a substrate binding synthetic molecule.

Question 37 of 100

What is the neoplastic cell of origin for this tumor?

  1. Lymphocyte

  2. Monocyte

  3. Macrophage

  4. Mononuclear phagocyte

 

PREFERRED RESPONSE: 4- Mononuclear phagocyte

DISCUSSION

Tenosynovial giant-cell tumors are widely known as pigmented villonodular synovitis (PVNS), although this term is misleading because this tumor type is a clonal neoplasm and does not involve an inflammatory process. It often is shown to have a t(1:2)(p13q37) karyotype resulting in CSF1-COL6A3 gene fusion. There are various amounts of mononuclear cells, osteoclastlike giant cells, foamy histiocytes, hemosiderophages, and chronic inflammatory cells. Local recurrences are common, but CSF1R inhibitors are being investigated in studies involving local control improvement and disease regression.

Targeted therapy trials to assist in control of the diffuse-type tenosynovial giant-cell tumor (formerly called PVNS) involve the use of monoclonal antibodies that inhibit CSF1R activation. CSF1R-expressing mononuclear phagocytes are affected by these monoclonal antibodies.

Infantile fibrosarcoma is associated with the t(12;15)(p13;q25) karyotype and ETV6-NTRK3 gene fusion product. Nodular fasciitis is associated with the t(17;22)(p13;q13.1) karyotype and MYH9-USP6 gene fusion product. Inflammatory myofibroblastic tumor is associated with translocations involving 2p23 resulting in multiple fusion products of ALK with TPM4 (19p13.1), TPM3 (1q21), CLTC (17q23), RANBP2 (2q13), ATIC (2q35), SEC31A (4q21), and CARS (11p15). No

nonpreferred response has a histologic appearance that includes hemosiderin, foamy histiocytes, and osteoclastlike giant cells.

A conformation-specific inhibitor of the juxtamembrane region of CSF1R is a synthetic molecule that is designed to access the autoinhibited state of the receptor through direct interactions with the juxtamembrane residues embedded in the adenosine 5’-triphosphate-binding pocket. It is designed to bind in the regulatory a-helix of the N-terminal lobe of the kinase domain in neoplastic cells of tenosynovial giant-cell tumor that have expression of the CSF1 gene. There is a structural plasticity of the domain of the CSF1R that allows the molecule to directly bind the autoinhibited state of CSF1R.

Another approach involves the development of the anti-CSF1R antibody, emactuzumab, which targets tumor-associated macrophages. A lower percentage of volume reduction has been reported with imatinib, a tyrosine kinase inhibitor. Alkylating agents have not been used in this benign neoplasm.

Tenosynovial giant-cell tumor is characterized by an overexpression of CSF1. CSF1R activation leads to recruitment of CSF1R-expressing cells of the mononuclear phagocyte lineage.

RECOMMENDED READINGS

CLINICAL SITUATION FOR QUESTIONS 51 THROUGH 54

Figures 51a and 51b are the radiographs of an 83-year-old active, independent, and healthy woman who has experienced 2 months of right lower thigh and knee pain. Her arthroplasty was previously well functioning, but her pain has increased progressively for several weeks. While exiting a car she “bumped” her knee against the door, felt a “crack,” and developed excruciating pain. She can no longer ambulate and was brought to the hospital

 

 

 

Question 51 of 100

Based on imaging alone, what does this bone lesion most closely resemble?

  1. Multiple myeloma

  2. Implant-associated osteolysis

  3. Metastatic renal cell carcinoma

  4. Enchondroma

 

PREFERRED RESPONSE: 4- Enchondroma

 

Question 52 of 100

Figures 52a through 52c show the biopsy of this lesion. Based on the clinical history, radiograph, and biopsy, which diagnosis is most likely?

  1. Enchondroma

  2. High-grade osteosarcoma

  3. Metastatic renal cell carcinoma

  4. Dedifferentiated chondrosarcoma

 

 

 

 

PREFERRED RESPONSE: 4- Dedifferentiated chondrosarcoma

 

Question 53 of 100

Staging for patients with this diagnosis necessitates which study or studies?

  1. CT scan of the chest and a bone scan

  2. Skeletal survey

  3. Bone marrow aspirate

  4. Bone marrow biopsy

 

PREFERRED RESPONSE: 1- CT scan of the chest and a bone scan

 

Question 54 of 100

Which local treatment option is most appropriate?

  1. Radiation and wide surgical resection

  2. Extended curettage with adjuvants

  3. Wide surgical resection

  4. Revision knee arthroplasty

 

PREFERRED RESPONSE: 3- Wide surgical resection

DISCUSSION

This patient has a pathologic femur fracture. Her history of antecedent pain in the context of a previously well-functioning implant suggests that a new process such as dedifferentiation of a long-standing lesion may have occurred. The initial radiograph reveals a well-mineralized lesion within the intramedullary canal with punctate calcifications. This by itself suggests an enchondroma or low-grade chondrosarcoma. It is important to note that enchondromas in the long bones rarely cause pathologic fractures. This is not the case when they are present in the hands and feet, where enchondromas frequently have a more aggressive radiologic appearance and pose higher risk. Radiographic findings concerning for malignant dedifferentiation of an enchondroma

include cortical thinning or breach, a soft-tissue mass, or periosteal elevation. The pathologic fracture obscures the ability to identify these hallmarks of malignant degeneration.

Multiple myeloma, renal cell carcinoma, and osteolysis are all typically radiolucent. Implant-associated osteolysis lesions are commonly multiple and periarticular. The histopathology reveals a cartilage tumor. The chondroid tissue appears to be low grade. However, in an adjacent region there is a high-grade component seen both on the low-power view and the second higher-power sample that does not resemble cartilage. This is highly suggestive of a dedifferentiated chondrosarcoma. This component signifies that a portion of the original tumor (low-grade chondrosarcoma), which resembled the tissue of origin, converted into a different cell lineage with more aggressive properties (nearly any type of high-grade sarcoma). Dedifferentiated chondrosarcoma is a highly aggressive malignancy, with average 5-year survivals of less than 50%. As with most sarcomas, the most likely site of metastatic dissemination of chondrosarcoma is pulmonary. Consequently, standard staging entails a high-resolution CT scan of the lungs.

Serum protein electrophoresis and a skeletal survey are used for diagnosis of multiple myeloma. Positron emission tomography/CT fusion scans are used at many centers in the staging of osteosarcoma, but their role in chondrosarcoma staging is an emerging modality that is being investigated. Radiation is not typically used for local treatment of extremity chondrosarcoma. Extended curettage is not appropriate for a high-grade lesion such as this. Revision arthroplasty alone does not address the tumor. Wide resection is the local treatment of choice for high-grade chondrosarcoma; because of the fracture, this patient may require an amputation to achieve wide margins.

RECOMMENDED READINGS

This is the last question of the exam.

GOOD LUCK

Dr. Mohammed Hutaif

About the Author: Prof. Dr. Mohammed Hutaif

Vice Dean of the Faculty of Medicine at Sana'a University and a leading consultant in orthopedic and spinal surgery. Learn more about my expertise and achievements.

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