Finger pathology is wide and includes all lesions involving the tendons, ligaments, muscles, bone, and articulations of the hand and foot digits.
brachydactyly - short digits
brachymetatarsia - short metatarsal
arachnodactyly - elongated, thin "spider-like" digits 1
Spinal epidural cystic lesions are fluid-filled lesions within the spinal canal but outside the thecal sac. Their clinical significance is as a potential contributor to spinal cord or nerve root impingement. Simple appearing spinal epidural cysts may represent several entities that differ by ori...
Intraosseous gas, also known as osseous pneumatosis, refers to the accumulation of gas bubbles within the cortical bone, trabecular bone, the bone marrow, or in the medullary cavity.
Intraosseous gas is an uncommon finding and differentials include 1,2:
Maxillodental leave alone lesions are usually incidental findings that do not require treatment nor follow-up if the patient is asymptomatic.
This article includes findings from orthopantomogram, cone-beam CT, and sinus CT studies.
Do not touch:
Leave alone lesions of the skull base refers to incidental findings that do not require treatment nor follow-up.
This article includes findings from brain CT, HRCT of the temporal bone, and MRI studies.
Do not touch:
arrested pneumatization of the skull base - sphenoid benign fatty lesion 1
Vacuum phenomena describe aseptic gas collections (e.g. nitrogen and traces of oxygen and or carbon dioxide) within different specific tissues 1-3. Usually, they are seen within the intervertebral discs, the bones and within different joints, but can also be seen in other usually adjacent locati...
Snowsport injuries cover a broad range of activities from skiing and snowboarding to recreational play (e.g. tobogganing, tubing).
Snowsports are popular with over 70 million people globally participating each year 1. While the injury rate varies depending on location, a rough ave...
Intra-articular gas or air (pneumarthrosis) can occur from a number of varied pathologies and should be interpreted according to the clinical context.
compound injury with gas entering from the outer surface
can occur with a pneumolipohaemarthrosis
Coarse trabecular bones can result from a number of causes 1,2:
Paget disease (bone)
hemaglobinopathies, e.g. thalassemia, chronic iron deficiency anemia 3
coarse trabecular pattern in bone (mnemonic)
Overhead elbow sports injuries are a group of pathologies seen in sports activities with overhead throwing or strokes, e.g. tennis, volleyball, baseball, javelin throwing. There has been a tremendous increase in the number of participants in these sports activities worldwide.
Here is a list of some of the most useful differential diagnoses in musculoskeletal imaging.
lucent/lytic bone lesions (FEGNOMASHIC)
multiple lucent/lytic bone lesions
benign lytic bone lesions in patients under 30 years old
diffuse bony sclerosis
permeative process in bone
The differential diagnosis for a dense base of the skull includes:
Van Buchem disease
Synovial enhancement is an imaging feature typically observed on MRI imaging. It can occur in various forms and can be focal or diffuse.
transient synovitis of the hip
tuberculous septic arthri...
Diffuse T1 vertebral bone marrow signal loss is associated with replacement of fatty marrow by edema or cellular tissue.
T1-weighted imaging without fat suppression is one of the most important sequences for distinguishing between normal and abnormal bone marrow. Ab...
The musculoskeletal manifestations of cystic fibrosis are uncommon compared to the well known respiratory manifestations.
For general discussion of cystic fibrosis, and a discussion of its other manifestations, please refer to:
cystic fibrosis (parent article)
pulmonary manifestations of cys...
Cervical spine injuries can involve the cervical vertebral column, intervertebral discs and cervical spine ligaments, and/or cervical spinal cord. The cervical spine accounts for ~50% of all spinal injuries.
5-10% of patients with blunt trauma have a cervical spine injury 1.
The pattern of bone bruise in knee injuries (a.k.a. bone contusion) can give clues for the mechanism and associated injuries.
Five classic bone contusion patterns have been described 1-4:
valgus stress to flexed and externally rotated knee
Tibiotalar slant is the superolateral inclination of the tibial plafond, and results in an ankle valgus deformity. There are a number of causes 1:
trauma, i.e. distal tibial fractures
osteomyelitis and/or septic arthritis
juvenile idiopathic arthritis
sickle cell dis...
There are many causes for mandibular periostitis:
Langerhans cell histiocytosis
malignancy (both primary and metastatic)
necrosis, e.g. radiation osteonecrosis
Garre's sclerosing osteomyelitis
The list of causes of a generalized periosteal reaction overlaps that of symmetrical periosteal reaction, and includes 1,2:
vascular stasis (common)
infantile cortical hyp...
There are a large number of causes for a symmetrical periosteal reaction 1,2:
age < 6 months
physiologic periostitis, most common cause before 6 months old
age > 6 months
chronic venous insufficiency
juvenile idiopathic a...
Patellar tumors are extremely rare. They can be either benign or malignant primary bone tumors, or metastases.
Patellar tumors represent just 0.1% of all primary bone tumors 1.
Patients may present with anterior knee pain and/or a palpable mass 1,3.
Juvenile osteoporosis refers to osteoporosis occurring in children.
It can arise from a number of causes 1-4:
osteoporosis pseudoglioma syndrome
Torticollis, also known as wry neck, is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the pediatric age group.
Torticollis can be acute (<1 wee...
There is only a short list of terminal tuft masses, which can arise from the adjacent soft tissues and erode the terminal tuft as well as arising from the terminal tuft itself:
epidermal inclusion cyst: history of penetrating trauma
tenosynovial giant cell tumor: occur laterally
A high bone mineral density is one where the bone mineral density (BMD) is usually greater than two standard deviations above what is expected for age. This can sometimes be seen on routine DEXA scan assessment. Some authors advocate a definition of a high BMD where the Z-score is greater than +...
Empyemas are purulent inflammatory collections within a body cavity. Contrast this with abscesses, which arise within parenchymal tissue, rather than occupying a pre-existing anatomical space.
Colloquially, the standalone term empyema is used to refer to thoracic empyemas but there...
Loss of intervertebral disc space can be due to a variety of causes:
degenerative disc disease of the spine: most common cause
dialysis related spondyloarthropathy
crystal deposition diseases
Anterior knee pain is common with a variety of causes which can be divided anatomically using a layered approach1 from superficial to deep:
Superficial soft tissues
quadriceps tendinosis / partial tear
Periosteal reaction in the pediatric population, also known as periostitis in children, is relatively common occurrence and can result from many causes.
The differential diagnosis for multiple bone periostitis include but not limited to the following:
There are many types of talar dislocation given its multiple articulations:
total talar dislocation
Talar fractures are an uncommon injury, accounting for <5% of all foot fractures. Recognition of the unique talar anatomy is important for correct diagnosis.
talar head fractures
talar neck fractures
talar body fractures
talar dome osteochondral fracture
Tumors that metastasize to bone may be remembered using the mnemonic "PBKTL", rendered as "lead kettle", as "Pb" is the standard abbreviation for the chemical element, lead.
For females, breast and lung are the most commo...
There is broad differential for cyst-like lesions around the knee.
popliteal synovial cyst - Baker cyst
intra-articular ganglion cyst
ACL ganglion cyst
PCL ganglion cyst
Hoffa fat pad ganglion cyst
extra-articular ganglion cyst
Gracile bones refer to changes in the skeleton in which the bones are more slender than usual (over-tubulated) and occasionally deformed in other ways such as being abnormally curved. This may occur in a number of disorders and can occur with or without fractures.
Pencil-in-cup deformity is the description given to one of the appearances on plain radiographs classically associated with psoriatic arthritis; however, it is not pathognomonic.
The appearance results from periarticular erosions and bone resorption giving the appearance ...
Supernumerary ribs occur most commonly as a cervical rib arising from C7 or a lumbar rib arising from L1. In extremely rare situations, there can be sacral, coccygeal, intrathoracic, or aberrant lumbar ribs 3. Rarely supernumerary ribs (cervical and lumbar ribs aside) have been found as 'normal'...
≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including:
Down syndrome (trisomy 21)
asphyxiating thoracic dysplasia (Jeune syndrome)
short rib polydactyly syndromes
chromosome 1q21.1 deletion...
Myonecrosis is a myopathy involving infarction of skeletal muscle and can have the appearances of an intramuscular mass.
Myonecrosis represents an infarction of the skeletal muscles. It has a variety of causes 1-3:
post-traumatic (see: calcific myonecrosis) - most common
Differential diagnosis of erosion of the superior aspects of the ribs include:
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression, and obstructive hydrocephalus.
The craniovertebral junction...
The terms valgus and varus refer to angulation (or bowing) within the shaft of a bone or at a joint in the coronal plane.
It is determined by the distal part being more medial or lateral than it should be. Whenever the distal part is more lateral, it is called valgus. Whenever the distal part i...
Floating meniscus (also known as meniscal avulsion) occurs in acute traumatic settings when the meniscotibial coronary ligaments get disrupted leading to avulsion of the meniscus from the tibial plateau.
Displacement of the meniscus for 5 mm or more from the tibial p...
The metaphyseal blanch sign (or metaphyseal blanch sign of Steel) is one of the signs seen on AP views of the adolescent hip indicating posterior displacement of the capital epiphysis.
It is a crescent-shaped area of increased density, that overlies the metaphysis adjacent to the physis on the ...
Flowing ossifications are seen in diffuse idiopathic skeletal hyperostosis (DISH).
They are defined as heterotopic ossifications involving the anterior longitudinal ligament, paraspinal connective tissues and annulus fibrosus of at least four contiguous vertebral bodies and are originally descri...
Parasyndesmophytes or floating syndesmophytes are, as the name suggests, paravertebral dystrophic soft tissue calcifications or heterotopic ossifications.
They are known to be seen in 4:
Initially they begin ...
Solitary well-defined osteolytic lesions can be seen with the following conditions 1,2:
subchondral geodes or cysts
intraosseous tophus (gout)
unicameral bone cyst
aneurysmal bone cyst
epidermoid inclusion cyst
Ill-defined solitary osteolytic lesions can be caused by following entities 1:
giant cell tumor
fibrosarcoma of bone
malignant fibrous histiocytoma
Expansile lytic bone lesions without cortical destruction can result from various benign and malignant neoplastic pathologies, causes include 1:
unicameral bone cyst
aneurysmal bone cyst (eccentric)
chondromyxoid fibroma (eccentric)
non-ossifying fibroma (eccentric)
Bridging (or fusion) of the pubic symphysis can be associated with various systemic and local causes, including 1-3:
Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus. They are seen in only a limited number of conditions including:
They can be classified as...
Subcutaneous calcification can be associated with a number of disorders. The list includes:
basal cell nevus syndrome
as a manifestation of systemic lupus erythematosus
Hydroxyapatite crystal deposition disease (HADD) is a disease of uncertain etiology characterized by periarticular and intra-articular deposition of hydroxyapatite (HA) crystals.
The shoulder is the most frequently involved site with classic calcific tendinitis presentation.
Monoarticular arthropathy can result from a number of causes:
septic arthritis (8-27%)
rheumatoid arthritis (RA) (11-16%)
Less common 2:
HADD (hydroxyapatite deposition disease)
reactive arthritis 2
Polyarticular arthropathy can arise from a number of causes. The list includes
rheumatoid arthritis (RA)
calcium pyrophosphate dihydrate deposition disease (CPPD)
Erosive arthritis has a broad differential:
clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal women
typically the interphalangeal joints, 1st carpometacarpal joint 6, but not the metacarpophalangeal (MCP) joints and large joints
Common causes of periarticular soft tissue calcification include:
post surgical dystrophic calcification or heterotopic bone formation
calcific tendinitis or bursitis
calcific periarthritis (fingers and toes)
Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal.
Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
Diaphragmatic paralysis (also considered very similar to the term diaphragmatic palsy) can be unilateral or bilateral.
Clinical features are highly variable according to underlying etiological factors:
unilateral paralysis: asymptomatic in most of the patients as the oth...
Congenital limb amputation is the absence of a fetal limb or part of a limb that usually occurs due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
They are slightly more common in the upper limb (60%) than ...
Joint ankylosis has a relatively broad differential including 1-5:
chronic reactive arthritis
juvenile idiopathic arthritis
surgical ankylosis (arthrodesis)
Differential diagnosis of vertebral lesions is very wide.
Vertebral body origin
vertebral body osteomyelitis
giant cell tumor
Langerhans cell histiocytosis
A pseudoarthrosis (plural: pseudoarthroses) (a.k.a. false joint) is a mobile fracture non-union.
A fibrous, pseudosynovial capsule forms around the non-union and viscous fluid fills the site that may simulate synovial fluid.
failed bone graft
Monoarthritidies have a relatively short differential diagnosis, including:
Charcot joint (neuropathic joint)
tenosynovial giant cell tumor
Soft tissue lesions with predominantly low T1 and T2 signal have a reasonably long differential, including:
densely calcified/ossified lesions
Long bone metaphyseal cupping is most likely due to the local oligemia from thrombosis in the terminal epiphyseal arteries to the epiphyseal plate, induced by prolonged regional immobilization 7.
The differential diagnosis of long bone metaphyseal cupping includes:
Skeletal leave alone lesions, also called “do not touch” lesions, are so characteristic radiographically, that further diagnostic tests such as a biopsy are unnecessary and can be frankly misleading and lead to additional unnecessary surgery. Thus a radiologic diagnosis should be made without a ...
Metal-on-metal pseudotumors represent mass-forming inflammation around a metal-on-metal hip or knee replacement. The term describes one presentation on the spectrum of adverse reaction to metal debris.
Metal-on-metal pseudotumors are large focal solid or semiliquid masses...
The differential diagnosis for metaphyseal lesions includes:
aneurysmal bone cyst
simple bone cyst
giant cell tumor
Swan neck deformity is a musculoskeletal manifestation of rheumatoid arthritis presenting in a digit of the hand, due to the combination of:
hyperextension of a proximal interphalangeal (PIP) joint
flexion of a distal interphalangeal (DIP) joint
The swan neck deformity, characteriz...
The term sausage digit refers to the clinical and radiologic appearance of diffuse fusiform swelling of a digit due to soft tissue inflammation from underlying arthritis or dactylitis.
The common causes of sausage digit are
Very bizarre generalized lesions of bone tend to make you exclaim "Oh my! What is going here?" Although there are numerous potential causes, in this situation it is worth thinking of a number of entities:
skeletal dysplasias and metabolic diseases
Conditions associated with bone deformity from softening includes:
bowing of long bones
biconcave vertebral bodies / codfish vertebra
The gull-wing appearance, also known as seagull erosions or sawtooth appearance, is classically seen in erosive osteoarthritis, typically on posteroanterior radiographs of the hands, although has also been reported in psoriatic and rheumatoid arthritis. These erosions more commonly occur at the ...
A pseudopermeative process in bone has multiple small cortical holes that are then superimposed over the marrow, giving a similar appearance to a permeative process.
The most common pathologies that manifest with pseudopermeative appearance (and mimic permeative lesions) ar...
Lytic skull lesions have a relatively wide differential that can be narrowed, by considering if there are more than one lesion and whether the mandible is involved.
lytic skeletal metastases
epidermoid - scalloped border with a sclerotic rim
Complete fatty replacement of red marrow with fat on MRI can occur in a number of situations which includes:
regional radiation therapy
Complications of total hip arthroplasty are common and it is essential for the radiologist to be aware of them in the assessment of radiographs of total hip replacements. Complications are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered ...
Forefoot pain in the metatarsal region is a common complaint and may be caused by a number of conditions. It is worthwhile for a radiologist to have knowledge of the potential causes and their imaging features 1.
plantar plate disruption
Dystrophic soft tissue calcification is a type of soft-tissue calcification, which occurs in damaged or necrotic tissue, while the serum level of calcium and phosphorus are normal. It may progress to ossification, in which case a cortical and trabecular bone pattern is visible.
An often cited a...
Exostoses are defined as benign growths of bone extending outwards from the surface of a bone. It can occur in any bone and be triggered by a number of factors. There are a number of examples of exostoses that occur due to local irritant stimuli:
exostosis of the external audit...
Lytic bone (osteolytic) metastases are distant tumor deposits of a primary tumor within bone characterized by a loss of bone with the destruction of the bone matrix.
Lytic bone metastases are more common than sclerotic bone metastases.
The diagnosis is usually establis...
Mixed lytic and sclerotic bone (osteolytic and osteoblastic) metastases refer to metastatic bone disease with both sclerotic and lytic bone metastases or bone metastases with both components.
The diagnosis is established by proof of sclerotic and lytic bone metastases of one primary ...
Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions 1.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to b...
Medical devices in the abdomen and pelvis are important to be recognized, just like medical devices of the chest. We often ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Fetal rib fractures can be caused by certain skeletal dysplasias. These include:
osteogenesis imperfecta: type II - one of the classical causes of fetal rib fractures
achondrogenesis: type Ia - Houston-Harris sub type
Bone-forming tumors are a subset of bone tumors that are characterized by their propensity to form excess osteoid. They can be further subdivided into benign and malignant tumors.
ossifying fibroma 1
Frontal bossing is a calvarial radiographic feature where the front of the skull appears protruding anteriorly. It is best appreciated on a sagittal or lateral image.
This feature can be seen in many conditions (in alphabetical order):
Soft tissue calcification is commonly seen and caused by a wide range of pathology.
There is a wide range of causes of soft tissue calcification 1:
dystrophic soft tissue calcification (most common)
chronic venous insufficiency 2
The differential diagnosis for a vertebral body mass is broad and may range from a completely benign bone island to a malignant primary bone tumor.
Broadly, these lesions can be separated into:
primary bone tumors
secondary metastatic disease
Lethal skeletal dysplasias form a heterogeneous group that is commonly characterized as being non-survivable for prolonged periods ex-utero. They include (in alphabetical order):
chondrodysplasia punctata: lethal variants
The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent 5.
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to...
A shortened fetal humerus is a morphological description and is usually defined when the humeral length falls below the 5th percentile or less than 0.9 as predicted by the biparietal diameter (BPD). It can occur in isolation or in association with a number of other anomalies.
The humeral length...