FRCS Mock Exam 2: Clinical Reasoning

Multiple emboli. Donaldson et al have attempted to define this poorly understood phenomenon: “BCIS is characterized by hypoxia, hypotension or both and/or unexpected loss of consciousness occurring around the time of cementation, prosthesis insertion, reduction of the joint or, occasionally, limb tourniquet deflation in a patient undergoing cemented bone surgery.” Current thinking on aetiology leans towards multiple embolic showers of fat, marrow, cement particles, air, bone particles and platelet/fibrin aggregate. Previous theories of methylmethacrylate monomers entering the circulation and causing significant vasodilatation have now largely been discounted in favour of the embolic theory.

Movement Primary stabilizer Secondary stabilizers External rotation LCL and popliteofibular ligament PLC; MCL Valgus superficial MCL PMC, ACL Varus PMC, ACL ACL, PLC

Parathyroid hormone (PTH) acts directly on osteoclasts to stimulate bone resorption via carbonic anhydrase. PTH is an 84-amino-acid peptide, produced by the chief cells of the parathyroid glands. Its overall effect is to increase serum calcium levels, by action in the kidney (stimulation of hydroxylation of 25(OH)-vitamin D3 and increased reabsorption of filtered calcium) and in bone (bone resoprtion). It acts indirectly on osteoclasts via a secondary messenger mechanism via osteoblasts. 236

Ischial tuberosity. The pelvic apophyses appear in early adolescence and fuse around age 14–16. Avulsions therefore occur most commonly in teenagers during sporting activities. Football and gymnastics are commonly associated with these injuries. Avulsion of the ischial tuberosity is the commonest type caused by sudden hip flexion with knee extension such as striking a football. The diagnosis is usually apparent on plain radiographs. Avulsion injuries are best treated conservatively with a gradual return to sporting activity after 3 months. Unrecognized avulsions may heal with abundant callus and can be misdiagnosed as bone tumours. The situation can be clarified with CT or MR imaging.

The condition is more common on the lateral than medial femoral condyle. Osteochondritis dissecans is a lesion of subchondral bone that results in subchondral delamination and sequestration with or without articular mantle involvement. It is more common in males (5:3), bilateral in 20%, and more common on the medial femoral condyle (4:1). Healing potential is greater in younger patients and open growth plates are considered a good prognostic factor. Pappas classification describes the age at detection: I – below 12 years, II – 12 to 20 years and III – above 20 years. The Guhl classification is based on arthroscopic appearance: I – intact lesion, II – early separation (stable flap), III – partial detachment and IV – complete detachment.

Activity modification. Distal clavicular osteolysis is an uncommon cause of shoulder pain that can occur after acute injury or repetitive microtrauma. Initial treatment is non-surgical and includes activity modification and ACJ steroid injection. Arthroscopic resection of the distal clavicle should be considered in patients refractory to non-operative treatment.

Young woman, injured hill-running. In general, outcome following operative management of calcaneal fractures relies on the number of intra-articular fragments and the quality of articular reduction. A number of factors have been shown to be associated with a poor outcome and they include age >50, obesity, manual labourers, work insurance cases, smokers, bilateral fractures and vascular disease. In addition, men appear to do worse with surgery than women.

patients following correction of scoliosis by a cast or instrumentation. As a result of the curve correction, the angle between the SMA and the aorta is narrowed resulting in the compression of the third part of the duodenum. Initial treatment includes oral intake restriction, nasogastric suction and intravenous fluid administration. The majority of cases settle with conservative measures. In rare cases of failed non-operative treatment, surgical intervention is indicated.

Budd–Chiari syndrome. Neural tube defects (NTDs) are a spectrum of disorders caused by failure of the posterior neural elements to fuse at around 3–4 weeks’ gestation. The causes are multifactorial although a raised level of homocysteine, a consequence of folate deficiency, is strongly implicated. NTDs are either open or closed. Open lesions usually involve the entire central nervous system (CNS) with leakage of cerebrospinal fluid (CSF) and result from failure of primary neurulation. Closed lesions are usually localized to the spine and result from failure of secondary neurulation. Closed types are covered by an epithelial layer and neural elements are therefore not exposed. However, any overlying skin may be dysplastic and cutaneous stigamata such as a pit or a hairy patch may be noticeable. The effects of NTDs depend on their location and severity although paralysis (flaccid and/or spastic) and bowel and bladder incontinence are characteristic. A type II Arnold–Chiari malformation is the commonest associated condition: downwards displacement of the cerebellar tonsils through the foramen magnum which can lead to hydrocephalus and mental retardation. Budd–Chiari syndrome is occlusion of the hepatic veins and is unrelated to NTDs.

Epiphyseal hyperplasia Rubin classifies skeletal dysplasias according to their location of origin within the bone and whether due to over- or underactivity. Trevor’s disease is also known as ‘dysplasia epiphysealis hemimelica’ and is due to hyperplasia within the epiphysis (epiphyseal osteochondroma). It is now more common for dysplasias to be diagnosed genetically rather than radiologically. Hypoplasia Hyperplasia Epiphysis Spondyloepiphyseal dysplasia/multiple epiphyseal dysplasia Trevor’s disease Physis Achondroplasia Enchondromatosis Metaphysis Osteopetrosis Multiple hereditary exostoses Diaphysis Osteogenesis Diaphyseal dysplasia 192 following is not true? a. Posterior dislocation of the hip with fracture of the femoral head caudal to the fovea centralis is a type I fracture. b. A type III fracture is rare, in conjunction with femoral neck fracture. c. Posterior dislocation of the hip with fracture of the femoral head cephalad to the fovea centralis is a type II fracture. d. A femoral head fracture with associated fracture of the acetabulum is a type III fracture. e. A and D. following statements is false? a. Type I fractures are wedge fractures of the lateral plateau, displaced or undisplaced. b. Type III fractures show depression of the lateral plateau without an associated wedge fracture. c. Type II fractures are often seen in patients whose average age is over 50. d. Anterior cruciate ligament injuries are commonly seen in type V and VI injuries. e. A type V fracture consists of a wedge fracture of the medial and lateral plateaux with metaphyseal–diaphyseal discontinuity. a. On a mortise view, the tibiofibular overlap should normally be more than 4 mm. b. A Maisonneuve fracture is a high fibular fracture and involves disruption of syndesmosis. c. A Dupuytren’s fracture is a fracture-dislocation with a high fibular fracture. d. On an anteroposterior (AP) radiograph, the medial clear space should be less than 4 mm. e. The talocrural angle can be used to assess shortening. 198

Calcaneonavicular coalition. A painful flatfoot in a child is likely to be secondary to a tarsal coalition. The two commonest tarsal coalitions are talocalcaneal and calcaneonavicular. The anteater sign is visualized on a lateral radiograph of the foot, and is caused by the elongated anterior process of the calcaneum. It is associated with a calcaneonavicular coalition. The coalition may be fibrous, cartilaginous or osseous. Observation, orthoses or plaster immobilization are the initial management modalities. If non-operative treatment fails, surgical excision and soft tissue interposition is an option, although arthrodesis may be required if degenerative changes are present.

50%. Because of the morbidity and prolonged rehabilitation associated with tendon repair it is advisable to repair lacerations over 50% of the tendon width. The exception to this rule is if there is visible triggering under a local anaesthetic block it may be necessary to address this.

A posterior instrumentation should stop at the distal most tilted vertebra. Scheuermann’s kyphosis is a kyphotic deformity of >45
in the thoracic spine with >5
anterior wedging across three consecutive vertebrae. The condition is often associated with a lumbar hyperlordosis. A mild scoliosis can sometimes be present. It is differentiated from postural kyphosis by the rigidity of the curve. It is the most common cause of thoracic back pain in older children and adolescents. An MRI scan is indicated to look for disc herniation, cord abnormalities and spinal stenosis. Surgery is indicated for curves >80
in skeletally mature patients, it entails a posterior spinal fusion with dual-rod instrumentation þ/ anterior release and interbody fusion. The fusion level should stop distally at the vertebra which is parallel to the floor (usually the L3 level). A ligamentum flavum excision should be performed at the apex to prevent buckling of the ligament and therefore decrease the risk of neurological deficit.

Gestational diabetes. The two most important risk factors for developmental dysplasia of the hip are a positive family history and breech position. The other important risk factors are first 187 born children and female sex. Gestational diabetes is not particularly associated with developmental dysplasia of the hip.

External rotation deficit. Healing of the tuberosities and their attached rotator cuff tendons is crucial in functional outcome after arthroplasty. Failure to properly position tuberosity fragments in the horizontal plane may result in insurmountable post-operative motion restriction.

Synovial cell sarcoma. Although primary cutaneous melanoma is the most common malignant tumour of any type in the foot (acral lentiginous melanoma), the most common primary soft tissue malignant tumour in the foot is synovial sarcoma. They make up approximately 8–10% of all sarcomas and most commonly affect adults in the third to fifth decades of life. They are often seen as soft tissue swelling with calcification on plain radiographs. The characteristic histological feature is a biphasic pattern with an epithelial component and a spindle cell component. Other common tumours or tumour-like conditions in the foot include enchondroma, osteoid osteoma, fibrous dysplasia, adamantinoma, osteochondroma, ganglion, clear cell sarcoma and fibromatosis.

It exhibits a high Young’s modulus. PMMA or bone cement is used widely in orthopaedics, principally with implants. It is strongest in compression, but its disadvantages include its poor tensile and sheer strengths. Its Young’s modulus is comparatively low (see question 18), and is between that of cortical and cancellous bone.

Closed or open reduction and combined screw and K-wire stabilization. The tarsometatarsal joint is best thought of in three columns: a medial column (first tarsometatarsal joint), a middle column (second and third tarsometatarsal joints) and a lateral column (fourth and fifth tarsometatarsal joints). Any dislocation or subluxation needs reduction. A cast or external fixator does not hold the reduction adequately. Although there are many ways to stabilize the fracture-dislocation after reduction, it is generally accepted that the medial and middle columns should be treated with permanent fixation (for example screws) and the lateral column should have temporary fixation (for example K-wires removed after 6–12 weeks). This is due to the relatively greater mobility of the lateral column.

Transforming growth factors. Bone morphogenetic proteins (BMPs) are multifunctional growth factors that belong to the transforming growth factor beta (TGF-b) superfamily.

Albright’s hereditary osteodystrophy. Brachydactyly refers to short first, fourth and fifth metacarpals and metatarsals. This is seen in pseudohypoparathyroidism, otherwise known as Albright’s hereditary osteodystrophy. This disorder occurs due to a parathyroid hormone (PTH) receptor abnormality. In addition to the brachydactyly, patients are obese, have reduced intelligence and can present with exostoses.

Chondrocyte number increases in ageing. Chondrocyte numbers decrease in ageing cartilage. The others are all true: Osteoarthritis Ageing Water content Increases Decreases Proteoglycan degradation Increases Decreases Chondrocyte number Decreases Decreases Young’s modulus of elasticity Decreases Increases

Cross the physis. Giant cell tumour of bone occurs in young adults aged 25–40. The physis must be closed for the radiological criteria to be met which are: 1. Epiphyseal location, 2. Abut the articular surface, 3. Eccentric, 4. Non-sclerotic margin. The most common sites in the appendicular skeleton are the distal femur and distal radius. The sacrum is the commonest site in the axial skeleton.

Decreased chondroitin 4-sulphate concentration. Chondroitin sulphate concentration increases in osteoarthritis and this includes both chondroitin 4- and 6-sulphate. Keratin sulphate concentration decreases and hence the ratio of keratin to chondroitin sulphate decreases as well.

Arthritis. Post-traumatic arthritis is the most common complication following Lisfranc injuries. The major determinant of a good result is anatomical reduction. Patients with purely 214 ligamentous injury tend to have outcomes, even with anatomical reduction and screw fixation.

Interleukin-6 (IL-6). Multiple cytokines have been measured in serum. Elevated levels of IL-6 have been associated with the development of MODS.

Gram-positive coccus Gram-negative coccus Gram-positive bacillus Gram-negative bacillus Steptococcus Actinomyces Escherichia coli Coryneform Salmonella typhi Diphtheroids Klebsiella pneumoniae Helicobacter pylori

HLA B27 positivity. Modified New York Criteria for diagnosing ankylosing spondylitis: Clinical criteria: Low back pain; present for more than 3 months; improved by exercise but not relieved by rest. Limitation of lumbar spine motion in both the sagittal and frontal planes. Limitation of chest expansion relative to normal values for age and sex. Radiological criterion: Sacroiliitis on X-ray. Diagnose: Definite ankylosing spondylitis if the radiological criterion is present plus at least one clinical criterion. Probable ankylosing spondylitis if three clinical criteria are present alone, or if the radiological criterion is present but no clinical criteria are present.

Nail patella syndrome. This syndrome is a result of an abnormality on chromosome 9. Patients may have subluxed or dislocated radial heads and never realize they have a problem until they have an X-ray. The syndrome can include abnormalities of the patella and nail growth, generalized ligamentous laxity and bony exostoses.

C-reactive protein (CRP) >20. Due to the rapid chondrolytic effect of pus within the joint, pyogenic septic arthritis of the hip in children represents a surgical emergency. It can be difficult to distinguish a septic hip from other causes of hip pain in children. In such cases, whilst clinical suspicion remains of paramount importance, Kocher’s diagnostic algorithm is a useful tool. The four diagnostic criteria are non-weight-bearing, ESR >40, WBC >12 and fever. The predicted risk of a septic arthritis varies with the number of positive criteria. The algorithm has been tested retrospectively and prospectively. In the prospective validation study the probabilities were lower: Number of criteria met Chance of septic arthritis (original study) Chance of septic arthritis (validation study) 3% 40% 35% 93% 73% 93%

Claw toe. These features describe a claw toe deformity. A hammer toe is only flexed at the proximal interphalangeal joint and a mallet toe is only flexed at the distal interphalangeal joint. A bunionette is characterized by a prominence of the fifth metatarsal head. 137 has lost 3 kg in weight but is otherwise well. He is pale, apyrexial and his right knee is slightly swollen and warm on examination. Plain radiographs reveal areas of dense sclerosis admixed with areas of radiolucency in the distal femoral metaphysis. Aggressive periosteal new bone formation is also noted. Which of the following is the most likely diagnosis? a. Parosteal osteosarcoma. b. Periosteal osteosarcoma. c. High-grade intramedullary osteosarcoma. d. Telangiectatic osteosarcoma. e. Osteomyelitis. of all of the following except? a. Anti-shock protein 90 antibodies. b. Chemokine receptor type 4(CXCR-4). c. Alkaline phosphatase (ALP). d. Vascular endothelial growth factor (VEGF). e. P-glycoprotein. her left wrist. She has also recently been having repeated episodes of abdominal discomfort, nausea and vomiting. A plain radiograph of the wrist reveals an eccentrically placed lytic lesion in the metaphysis and epiphysis with thinning of the cortex. You suspect a giant cell tumour of bone. What is the most appropriate next step in the management of this patient? a. Perform a bone biopsy. b. Curettage alone. c. Curettage and phenolization. d. Curettage, high-speed burr, cement and bone graft. e. Check serum parathyroid hormone (PTH) and calcium. 144

The causative organism is Pasteurella multocida. Cat scratch disease is caused by a wound inflicted by a cat. It causes infection of the lymphatic system by Bartonella henselae. Treatment can be supportive as the disease resolves in 2–6 months. Symptomatic treatment in the form of aspiration of painful lymph nodes is acceptable. Incision and drainage of these nodes is contraindicated. The antibiotic of choice is azithromycin. Pasteurella multocida is the causative organism in cat bite injuries.

Lateral cutaneous nerve of thigh. The ilio-inguinal approach is an exam favourite. It affords exposure to the inner aspect of the pelvis from the sacroiliac joint all the way to pubic symphysis. The lateral cutaneous nerve of thigh often is in the way and must be sacrificed. Although infrequently used by 86 most surgeons, it would be worth memorizing the concepts of this approach, particularly the structures at risk in the three ‘windows’: Lateral – between the iliac wing and the iliopsoas muscle; Middle – between the femoral nerve (iliopsoas muscle) and the external iliac vessels; Medial – between the lymphatics and the rectus abdominus at the level of the pubic tubercle.

Internal fixation of the symphysis pubis and internal fixation of the sacrum. Pelvic ring injuries must be assessed for stability, according to the pattern of injury. Classification is either by Tile: A – stable B – partially stable (rotationally unstable, vertically stable) C – unstable (rotationally unstable, vertically unstable) or by Young–Burgess: Anteroposterior (AP) compression Lateral compression Vertical shear Combined This injury described is unstable and requires both anterior and posterior fixation.

Clinodactyly. The causes of congenital hand anomalies may be classified according to Swanson and the IFSSH (International Federation for Societies for Surgery of the Hand) system: failure of formation, failure of differentiation, duplication, hyperplasia, hypoplasia, amniotic bands, generalized dysplasias or combinations thereof. Clinodactyly (failure of differentiation) is a fixed ulna bowing usually of the little finger. Brachysyndactyly (failure of differentiation) means short digits with webbing between. Camptodactyly (failure of differentiation) is characterized by fixed flexion deformity usually of the interphalangeal joints of the little fingers. Acrosyndactyly is a form of constriction band syndrome which joins digits previously separated. Symphalangism (failure of differentiation) is a congenital ankylosis usually affecting the proximal interphalangeal joints.

The highest incidence is seen between the ages 8 and 13. The flexion is usually caused by muscle spasm and haemarthrosis. In type III fractures, the bone fragment may block full extension. The injury is most likely visualized on the lateral radiograph. Aspiration of a tense haemarthrosis is advised. In a type II fracture, bony union is possible without reduction manoeuvres.

An ipsilateral far lateral disc herniation at L5–S1. A paracentral disc herniation at L4–L5 or a far lateral disc herniation at L5–S1 most commonly result in an L5 radiculopathy and therefore weakness of the gluteus medius, resulting in a Trendelenburg gait. A paracentral herniation at L5–S1 most commonly affects the S1 nerve root. A paracentral herniation at L3–L4 and a far lateral herniation at L4–L5 all affect the L4 root.

Remove metalwork, insert cemented stem passing two cortical thicknesses below lowest screw hole. There is no need to reinforce the femur externally. A well-cemented stem must pass well past the lowest screw hole to reduce the risk of a stress riser. Hip resurfacing in a patient of this age is not recommended.

A varus malunion causes decreased eversion. Talar neck fractures are the commonest fracture of the talus, and follow forced dorsiflexion with axial load. They present a difficult problem, mainly due to the high complication rate, particularly osteonecrosis and post-traumatic osteoarthritis. The Hawkins classification is used for these fractures: I – undisplaced II – associated subtalar dislocation III – associated subtalar and tibiotalar dislocation IV(added by Canale) – associated subtalar, tibiotalar and talonavicular dislocation Type I injuries can be treated non-operatively, but the others need reduction and fixation. Hawkins sign refers to a subchondral lucency see on an anteroposterior radiograph at 6 to 8 weeks, and represents resorption, implying good vascularity, and hence is a good prognostic sign. A varus malunion occurs in one-third of cases and results in decreased eversion.

‘slip angle’ is commonly used but is rarely defined: it usually refers to the Southwick angle (with or without subtraction of the normal side). Severe slips treated with pinning in situ show poorer results than mild and moderate slips. The metaphyseal blanch sign is a radiographic sign of SUFE seen on the AP pelvic radiograph. It can be seen even with minor slips. Recent publications suggest that AVN complicates 20% of acute, severe unstable slips. AVN is also a complication of subcapital osteotomy. It is not an indication for such an osteotomy. Femoral retroversion puts stress across the physis and is a mechanical factor associated with development of a SUFE. Endocrinopathy is a potential cause of SUFE and may guide the surgeon towards prophylactic pinning of the unaffected hip.

There is a known organism from preoperative aspirate and the patient has commenced antibiotics. Selected patients may undergo single-stage revision, with reported better functional outcome than two-stage revisions. The prerequisites for this are healthy soft tissues, minimal bone loss allowing for cement to be inserted, and a known pathogen with sensitivities. Significant severe bone loss, an unidentified pathogen and the presence of multi-resistant bacteria are contraindications to single-stage revision surgery.

A space available for the cord (SAC) of less than 14 mm or an ADI of more than 9–10 mm is an indication for spinal stabilization. An atlantoaxial subluxation occurs in 60–80% of cases of rheumatoid arthritis (RA) as the result of pannus formation at the synovial joints between the dens and the ring of C1. An ADI of >3.5 mm on flexion extension is a common finding in RA and indicates instability; however, it is not necessarily an indication for surgery. A SAC <14 mm or an ADI >9–10 mm is associated with an increased risk of neurological injury and usually requires surgical intervention. A Ranawat C1–C2 index is the distance from the centre of the C2 pedicle to a line connecting the anterior and posterior arches of C1. It is the most reproducible measurement of invagination. A C1–C2 index <13 mm indicates basilar invagination. Subaxial subluxation occurs in 20% of cases of RA, a subluxation >4 mm or more than 20% of the body is indicative of cord compression.

Decompression of the syrinx in patients above the age of 10 years will improve or stabilize the scoliotic curve. Syringomyelia usually results from lesions that partially obstruct cerebrospinal fluid (CSF) flow including craniocervical junction abnormalities (Chiari malformations), spinal cord trauma and tumours. It often presents with central cord syndrome. Light touch, proprioception and vibration sensation are usually preserved. In most patients over the age of ten, surgical treatment of scoliosis is most likely necessary due to a large initial scoliosis curve or curve progression even after syrinx drainage.

The ligament of Struthers. The leash of Henry refers to the recurrent branches of the radial artery in the forearm. The arcade of Frohse is the tendinous proximal border of supinator. The tendinous origin of ECRB is a potential site of compression. The ligament of Struthers is a fibrous band extending from a large bony projection of the humerus, known as the supracondylar process, to the medial epicondyle. It is probably present in less than 1% of humans, and may cause median nerve compression.

Nerve stimulation therapy. If symptoms are not severe and there is not significant and progressive neuropathy then non-operative management must be considered. This includes splintage, hand therapy, steroid injection and even yoga has been proven to be beneficial. Alternatively a patient could be referred for either open or endoscopic release.

Total elbow replacement. The Larsen classification of the rheumatoid elbow is based on plain radiographs and is graded I–V: Grade I – soft tissue swelling and osteoporosis. Grade II – mild narrowing of the joint space and some marginal erosion. Grade III – significant joint space narrowing. Grade IV – integrity of subchondral plates is breached by deep erosions. Grade V – total joint destruction

Posteromedial tibial bowing. Fibular hemimelia is a postaxial deficiency or dysplasia in which there is aplasia or variable hypoplasia of the fibula. There are a number of associated features comprising from distal to proximal: absent lateral rays and/or tarsal bones, tarsal coalition, ball and socket ankle, valgus ankle, anteromedial tibial bowing, flattened tibial spine, absent anterior cruciate ligament (ACL), genu valgum, hypoplastic lateral femoral condyle, lateral patellar subluxation, femoral hypoplasia, coxa vara and possibly a true proximal femoral focal deficiency (PFFD). Congenital posteromedial bowing of the infantile tibia is considered ‘benign’ in that the deformity improves with growth. However, there is often a significant residual leg length discrepancy. 186

Arthroscopy, excision and microfracture. The Berndt and Harty classification refers to osteochondral lesions of the talus. It is a radiographic classification: I – compression of the subchondral bone II – a partially detached osteochondral fracture III – completely detached, non-displaced fragment IV – a detached and displaced osteochondral fragment Osteochondral lesions of the talar dome are commonly anterolateral or posteromedial; they are often traumatic in origin, particularly the anterolateral lesions, but may also have an osteonecrosis/atraumatic aetiology. Type IV lesions are best treated by excision and microfracture, with good results in up to 86% of patients. Microfracture is usually undertaken arthroscopically. If simple debridement and microfracture is ineffective in reducing symptoms, chondral or osteochondral grafting is considered. Ankle arthrodesis or arthroplasty is the definitive treatment.

Superficial palmar arch. The superficial palmar arch is a continuation of the ulna artery. In the majority of patients (78%) this arch is completed by branches from the deep palmar, radial or median arteries. This explains why even with significant lacerations to the ulna artery a hand can be well perfused. 20

Femoral head/neck junction prominence. The patient is likely to be suffering from cam-type femoro-acetabular impingement, often presenting secondary to DDH, Perthes, or slipped upper femoral epiphysis, with a head/ neck junction prominence that may also lead to labral degeneration, cysts and tear. Degenerate changes at the articular surface in mild DDH is rare in a patient of this age, although cysts may be seen at the head/neck junction if there is impingement.

Valgus deformity of femoral neck. All the above are seen due to remodelling of bone and high vascularity, except a valgus deformity. Typically, varus deformity is seen due to initially osteoporotic change which causes deformity under loading before remodelling into its final shape; this is also responsible for anterolateral diaphyseal bowing. Stress fractures may also be seen on the convex side of the femoral diaphysis. Bone may have lytic lesions or be unusually dense, depending on the activity of the disease process.