MSK EXAM MASTER 2022(CORRECTLY ANSWERED);250 QUESTIONS AND ANSWERS
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Case Ico-delete Highlights
Following a fall, a 6-year-old boy has restricted movement of the right hand. On examination, the right shoulder appears swollen. X-ray shows a fracture in the proximal humerus. However, at the site of fracture, there is a lucent defect extending up to the epiphyseal plate. The bone is not expanded. The patient undergoes a surgical procedure. Grossly, the lesion is actually cystic and contains clear yellow fluid. Microscopically, the cyst wall is made of fibrous tissue with occasional giant cells.
Question
What is the most likely diagnosis in this case? - Correct answer:
Simple cyst of bone
Explanation
Simple cyst of the bone is seen mainly in the proximal humerus and proximal femur in children. The patients generally present with a pathological fracture. X-ray shows a lucent defect situated centrally that extends up to the epiphyseal plate. Bone involved is not expanded. Grossly, the cyst has a thin fibrous wall and it is filled with clear yellow fluid. Microscopically, the cyst wall is thin, fibrous, septa, with occasional giant cells. A peculiar calcified matrix like cementum may be present. Treatment is by aspiration of the cyst followed by injection of methylprednisolone acetate. If this fails, then surgery is advised.
An aneurysmal bone cyst is a non-neoplastic locally aggressive lesion of the bone typically seen in first 2 decades of life. There is a slight female preponderance for developing them. It involves the metaphyses of the long bones. X-ray shows characteristic purely lytic lesion involving the metaphyses of a long bone with an eccentric, blow out appearance and extension into the soft tissue, which is limited by a thin shell of new bone. Grossly, it shows cavities separated by septa. The spaces contain blood or serum. Microscopically, there are cysts of various sizes separated by septa. The septa are composed of loosely arranged spindle cells and benign giant cells. The spaces are lined by cuboidal cells. The septa show capillary proliferation. Areas may show relatively solid proliferation of cells. It is treated by simple curettage but they can recur.
Telangiectatic osteogenic sarcoma is a histological variant of osteogenic sarcoma. It is characterized by prominent blood-filled cysts that appear similar to aneurysmal bone cysts radiographically and pathologically. Pathological fractures are very frequent. However, the septum that separates the bloody cysts contains malignant stroma. They are associated with a more aggressive course than conventional osteogenic sarcoma.
A ganglion is a small cyst that is always located near a joint capsule or tendon sheath. It is commonly seen around the wrist joint. It arises because of cystic or myxoid degeneration of connective tissue. The cysts lack a true cell lining. The lesion may be multilocular, and it enlarges by coalescence of adjacent areas of myxoid change.
Synovial cysts are caused by the herniation of synovium through a joint capsule. Sometimes, it occurs due to massive enlargement of the bursa. The cyst will have a synovial lining, and it may be hyperplastic and contain inflammatory cells and fibrin. The synovial cyst that forms in the popliteal space is called as Baker's cyst. These cysts are associated with joint diseases leading to increased intra-articular pressure, such as degenerative joint disease, neuropathic arthropathy, and rheumatoid arthritis.
Case Ico-delete Highlights
A 49-year-old, right-hand dominant woman presents with a 2-week history of progressive pain in her right thumb and wrist area. She says that her thumb seems to "stick" in place upon movement. She states that she has never experienced this before. You ask her if she has been using her hands more often than normal, and she tells you she recently began to crochet a sweater for a family member. On physical examination, her pain is markedly exacerbated when she places her thumb into the palm of her hand, and you passively move her hand in an ulnar direction.
Question
What is the most likely diagnosis? - Correct answer:
de Quervain's tenosynovitis
Explanation
The clinical picture is suggestive of de Quervain's tenosynovitis. It occurs commonly in middle-aged women, precipitated by repetitive use of the thumb. The inflammation thickens the tendon sheath abductor pollicis longus and extensor brevis on the thumb side of the wrist. This can cause pain, swelling, and may cause the thumb to lock in place upon movement. The Finkelstein test (full flexion of thumb into palm followed by ulnar deviation of the wrist) will produce pain and is diagnostic of de Quervain's tenosynovitis.
Wrist arthritis causes pain on movement with evidence on radiographs, which is not seen in this patient.
A scaphoid fracture would have tenderness in the anatomical snuffbox, which is not described in this patient.
Dorsal wrist ganglion presents with a palpable mass.
Thumb arthritis presents with swelling over the carpometacarpal joint and pain on joint compression.
Case Ico-delete Highlights
A 6-year-old boy has gradually increasing sharp pain to his left anterior hip that seems worse at night. He is moderately overweight, but he remains active and plays baseball. There is no history of trauma. There is no redness, swelling, or fever; there is no involvement of the other hip. Ibuprofen does seem to help. There is also no family history of any bone or joint disease. His weight is at the 95th percentile with height at the 50th percentile. On exam, there is mild tenderness to palpation over his left anterior hip, but the rest of the exam is normal. Laboratory studies show a normal complete blood count, hemoglobin, sedimentation rate, platelets, and C reactive protein. Plain X-rays show a small round lytic lesion surrounded by mild reactive bone formation.
Question
Based on these findings, what is the most likely diagnosis? - Correct answer:
Osteoid osteoma
Explanation
Osteoid osteoma is a common benign bone tumor consisting of an ovoid or spherical nidus of osteoid-rich tissue with interconnected bone trabeculae on highly vascularized connective tissue. It ranges from 0.5 to 2 cm in size. It does not progress or have malignant potential. In fact, some lesions may regress spontaneously. Multinucleated giant cells, osteoclasts, and axons are frequently observed. There may be bone sclerosis around the central nidus. Most are cortical or periosteal, but 20% arise within the marrow. Most patients are 5 to 20 years old. Most commonly, the proximal femur and tibia are involved, although any bone may be affected. Pain is usually the presenting symptom and is frequently relieved with non-steroidal anti-inflammatory drugs (NSAIDs). Tenderness upon palpation may be elicited on exam; patients may also have disuse atrophy, painful scoliosis, or limb-length discrepancy. X-rays are the initial examination of choice to reveal the central nidus as a small spherical or oval lytic lesion surrounded by soft-tissue edema and possible reactive bone formation. Computed Tomography (CT) is also used for precise localization and as guidance for biopsy and ablation. The primary goal of treatment is pain control with NSAIDs; however, if pain is not controlled or complications such as neuropathy, synovitis, growth disturbance, or scoliosis develop, the lesion should be removed. Several techniques are available for ablation, including percutaneous radiofrequency, ethanol, laser, or thermocoagulation therapy under CT guidance. Surgical options include en bloc excision, curettage, or CT guided removal. Although small lytic lesions can be caused by infections or other benign neoplasms of the bone and leukemia, the history, physical findings, small size of the lesion, and location in the diaphysis make osteoid osteoma the most likely diagnosis.
Ewing sarcoma is a highly malignant primary bone tumor derived from bone marrow. Males are affected more frequently than females, and it most commonly presents in children and adolescents aged 4-15 years. It is especially infrequent in African Americans and Asians. Metaphyseal or diaphyseal areas of long and flat bones are both affected. The earliest symptom is intermittent pain that becomes intense and may radiate to the limbs, particularly with tumors in the vertebral or pelvic region. X-rays will show a long, permeative lytic lesion in the metadiaphysis and diaphysis of the bone with a prominent soft tissue mass extending from the bone, or it will show a lesion with poorly defined margins that is destroying the bone. Occult metastatic disease is usually present, requiring multi-drug chemotherapy as well as local disease control with surgery and/or radiation. Length of treatment varies depending on location and staging, but most patients undergo chemotherapy for 6-12 months and radiation for 5-8 weeks.
Legg-Calve-Perthes disease, a childhood hip disorder, results from infarction with idiopathic avascular necrosis of the bony epiphysis of the femoral head. It occurs bilaterally in 10-20% of children, and they usually present at 4-8 years of age. Children present with limp, pain, and reduced hip range of motion. Possible causes include trauma and developmental, inflammatory, and coagulation abnormalities. Risk factors include male gender, low socioeconomic group, presence of inguinal hernia or genitourinary tract anomalies, and low birth weight. Early radiological signs most commonly show a small femoral epiphysis, sclerosis of the femoral head with sequestration and collapse with fragmentation, slight widening of the joint space due to thickening of the cartilage, failure of epiphyseal growth, and the presence of joint fluid or joint laxity. Magnetic Resonance Imaging is more sensitive in detecting early disease. Treatment aims at maintaining containment of the femoral head within the acetabulum with abduction splints, casts, or surgically with an osteotomy of the proximal femur.
Osteomyelitis is an infective process that may involve all osseous components including the metaphyses of long bones, particularly the tibia or femur. Hematogenous spread most commonly occurs in infants and young children. Neonates have group B streptococci and Escherichia coli as the most commonly involved organisms, with 50% also having a septic joint. Beyond the neonatal period, the most common organisms involved are Staphylococcus aureus, group A streptococci, and Haemophilus influenzae type b. Infections in this age group may gain access from traumatic injuries or surgical procedures. Joint involvement is rare beyond the neonatal period. Untreated or inadequately treated infections can become chronic, with staphylococcus isolated most frequently. Clinical presentation of hematogenous osteomyelitis can be variable, ranging from acute pain with decreased movement of the affected limb and adjacent joint to possible swelling and redness. Systemic signs can include fever, malaise, and irritability. Following trauma onset may be insidious; despite localized pain, edema, and redness, the frequent absence of systemic signs can misleadingly suggest a superficial infection. Laboratory studies may show an elevated or normal leukocyte count where sedimentation rate and C-reactive protein are typically elevated. A blood culture is positive in 50% of cases. Diagnosis is based on the history and physical exam findings supported by a positive technetium-99 methylene diphosphonate bone scan. X-ray changes show swelling of tissue around the infection and periosteal reaction or new bone formation, but these may not be evident until 1 to 2 weeks after onset of symptoms. Eventually, bone destruction with lytic lesions will be visible. Successful treatment requires an appropriate antibiotic at sufficiently high dose and duration. For staph [Show Less]