The differential diagnosis of pediatric cervical lesions is commonly encountered in practice, unfortunately, the list is long.
Most lesions tend to be inflammatory 3:
non-tuberculous mycobacterial lymphadenitis
The clavicle is a unique bone and as such it often displays unique pathology. The following is an attempt to summarize pediatric clavicle abnormalities.
Pediatric bone tumors and tumor-like lesions of the clavicle
majority of clavicular tumors are malignant
Ewing sarcoma (most common)
Pediatric nasal cavity masses can occur within the nose or the nasopharynx. These masses are often found incidentally on imaging but can be readily apparent clinically.
The clinical features of these lesions tend to mimic upper respiratory processes and may result in dela...
Pediatric renal tumors and masses are another group of diseases (just like cystic renal diseases in both the adult and child) that are bewildering in their number, nomenclature and overlapping findings.
Wilms tumor: common in older children 1-8 years old
There are a wide range of primary malignancies that result in pediatric skeletal metastases 1:
leukemia: although not truly metastases
clear cell sarcoma: Wilms’ variant
Ewing sarcoma: lung metastases much more common
Pancreatic atrophy is non-specific and is common in elderly patients, although in younger patients it can be a hallmark of pathology. Most commonly it is associated with aging, obesity and end-stage chronic pancreatitis.
It occurs principally with fatty replacement of the pancreas (pancreatic ...
Pancreatic calcifications can arise from many etiologies.
Punctate intraductal calcifications
alcoholic pancreatitis (20-40%) 2
intraductal, numerous, small, irregular
preponderant cause of diffuse pancreatic intraductal calcification
gallstone pancreatitis (2%) 2
There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.
Classification based on function
exocrine: ~99% of all primary pancreatic neoplasms
pancreatic ductal adenocarcinoma ~90-95%
intraductal papillary muc...
Pancreatitis (plural: pancreatitides) refers to inflammation involving the pancreas.
It has various forms which can be classified in many, many ways according to time of onset, etiological agent or associated pathology.
interstitial edematous pancreatitis
Papillary lesions of the breast comprise a wide group and range from benign to malignant.
They develop as tufts of epithelium with a ﬁbrovascular core that arborizes into branching papillae and protrude into the duct lumen.
papilloma of breast / intraductal papilloma of the ...
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 ...
Paratesticular lesions have a long list of differential diagnoses:
epididymal cyst (most common epididymal mass)
scrotal tunica cysts
tunica vaginalis cyst
tunica albuginea cyst
spermatic cord lipoma
scrotal hemangioma: is often hypervascular on color Doppler, unlike ot...
A paratesticular mass may derive from a number of structures that surround the testicle within the scrotum; most commonly, they derive from the spermatic cord.
The masses can be categorized as benign (70%) or malignant (30%).
spermatic cord lipoma (most common par...
Parkinson-plus syndromes are a loose group of neurodegenerative disorders that are characterized by features of Parkinson disease but with other neurological symptoms/signs. They have a poor response to levodopa, and mostly have fairly characteristic neuroimaging features.
Conditions included ...
Parotid enlargement (also known as parotidomegaly) has a wide differential given the significant breadth of pathology that can affect the parotid gland. These can be separated by the standard surgical sieve approach into infective, inflammatory, immune, neoplastic, infiltrative, and congenital c...
Patella alta, or a high riding patella, describes a situation where the position of the patella is considered high. It may be idiopathic or may result secondary to a patellar tendon rupture.
Several conditions are known to be associated with patella alta, including:...
Patella baja (or patella infera) is an abnormally low lying patella, which is associated with restricted range of motion, crepitations, and retropatellar pain. If longstanding, extensor dysfunction may ensue with significant morbidity.
It is seen in a variety of clinical scenarios in...
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.
Some medical conditions are characterized by the presence of pathological gas i.e. gas/air found in a space, tissue, or organ, where it would not normally be expected to be.
prefix 'pneumo' is common, especially when it refers to gas within a body space/cavity e.g. pneumothorax
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
Neonatal hypoxic ischemic brain injuries can manifest in different patterns of involvement depending on the severity and timing of the insult. When considering the perinatal maturation process of the brain and the severity of an insult, it is possible to understand the various manifestations.
Pear-shaped (or teardrop-shaped) bladder is one whose normal round or ovoid shape has been extrinsically compressed to resemble a pear. The pear may be inverted or upright, depending on how the excess pelvic tissue compresses the bladder.
Causes of a pear-shaped bladder inc...
A pedunculated intratracheal mass has a variety of differential diagnoses:
benign tumor, e.g. hamartoma, chondroma, lipoma
metastasis to tracheal mucosa, e.g. renal cell carcinoma, melanoma
polyp, e.g. inflammatory, antrochoanal
Pelvic masses in females carry a broad differential diagnosis:
benign adnexal cyst
pelvic inflammatory disease
Extragynaecological masses, e.g. colorectal carcinoma, appendicular abscess, lymp...
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 ...
Periampullary tumors are those that arise within 2 cm of the ampulla of Vater in the duodenum.
Tumors that fall under this group include four main types of tumors 1,4 that will be approached in their specific articles:
pancreatic head/uncinate process tumors: includes pancreatic ductal adenoca...
Periapical radiolucencies are commonly observed findings on OPG and other dental/head and neck imaging modalities.
They can represent a number of pathologies:
periapical lucency related to apical periodontitis
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)
Peribronchovascular thickening is a broad imaging descriptive term usually used to describe thickening of any or a combination of the below:
peribronchovascular interstitial thickening
bronchial wall thickening: can be differentiated from true peribronchovascular thickening on cross-sectional ...
Pericardial fat pads are normal structures that lie in the cardiophrenic angle. They are adipose tissues surrounding the heart composed of the epicardial fat, which lies between the myocardium and visceral pericardium, and paracardial fat, which is adherent and external to the parietal pericardi...
Perilymphatic lung nodules follow perilymphatic channels and on imaging are typically subpleural, occur along fissures (perifissural nodules), interlobular septa and adjacent to the bronchovascular bundles.
Lung nodules in a perilymphatic distribution can be seen in asso...
Perinephric fluid collections post renal transplant are common. The appearance of a perinephric fluid collection after renal transplantation is often non-specific but may be partially differentiated by how long ago the transplant occurred.
Early post-transplant period (<4...
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:
Periosteal reaction, also known as periostitis or periosteitis, is a nonspecific radiographic finding that indicates periosteal irritation. Periosteal reactions may be broadly characterized as benign or aggressive, or more specifically categorized by pattern.
Benign versus aggre...
Periportal hyperechogenicity can result from many causes including:
schistosomiasis of the portal region
recurrent pyogenic cholangitis (oriental)
inflammatory bowel disease: has been described to give "echo-rich" periportal cuffing 2
Periportal hypoechogenicity can result from many causes:
orthotopic liver transplant rejection
malignant lymphatic obstruction
Peritoneal calcification is seen in a limited number of conditions that result in calcification of peritoneal structures. Therefore, the differential diagnosis is small:
psammoma bodies in malignancy (most frequently cystadenocarcinoma of the ovary): fine sand-like calcification
It is important to have a systematic way of approaching a case with per vaginal (PV) bleeding in the exam.
intrauterine fetal demise
There is a wide differential diagnosis of petrous apex lesions:
asymmetrical marrow / asymmetrical pneumatization
fat signal intensity on all sequences
petrous apex cephalocoele 4
CSF signal intensity on all sequences
A simple and popular mnemonic to remember the common suprasellar/parasellar/intrasellar masses is SATCHMO. The more comprehensive list includes:
pituitary adenoma (commonest in the adult population)
The five most common masses in the pituitary region are:
suprasellar pilocytic astrocytoma
Craniopharyngioma and suprasellar pilocytic astrocytoma are common in children, and pituitary macroadenoma, meningioma, aneurysm are mostl...
Pituitary region masses with intrinsic high T1 signal, also referred to as suprasellar hotspots, are relatively frequently encountered, and the presence of high T1 signal narrows the differential somewhat.
The differential can be divided by the substance causing the T1 ...
Placentomegaly is a term applied to an abnormally-enlarged placenta.
It can be associated with a number of maternal and fetal disorders which include:
chronic intrauterine infections
Pleural adhesions usually refers to the formation of fibrotic bands that span the pleural space, between the parietal and visceral layers of the pleura.
They may be local or diffuse. The presence of a pleural adhesion is one of the causes for a pneumothorax not to resolve.
Pleural calcification can be the result of a wide range of pathology and can be mimicked by a number of conditions/artifacts.
calcified pleural plaques from asbestos exposure: typically with sparing of the costophrenic angles
infection involving the pleura: e.g....
Pleural effusions are abnormal accumulations of fluid within the pleural space. They may result from a variety of pathological processes which overwhelm the pleura's ability to reabsorb fluid.
"Pleural effusion" is commonly used as a catch-all term to describe any abnormal accumul...
Pleural thickening is a descriptive term given to describe any form of thickening involving either the parietal or visceral pleura.
It can occur with both benign and malignant pleural disease. According to etiology it may be classified as:
benign pleural thickening
following recurrent inflam...
There are several tumors that can involve the pleura which can range from being benign to malignant. The list includes:
primary pleural tumors 5
pleural malignant mesothelioma
well-differentiated papillary mesothelioma
Pneumatoceles are intrapulmonary gas-filled cystic spaces that can have a variety of sizes and appearances. They may contain gas-fluid levels and are usually the result of ventilator-induced lung injury in neonates or post-infectious. They should not be mistaken for a cavitating lung mass.
Polyarticular arthropathy can arise from a number of causes. The list includes
rheumatoid arthritis (RA)
calcium pyrophosphate dihydrate deposition disease (CPPD)
Polyhydramnios refers to a situation where the amniotic fluid volume is more than expected for gestational age.
It is generally defined as:
amniotic fluid index (AFI) >25 cm
largest fluid pocket depth (maximal vertical pocket (MVP)) greater than 8 cm 6: although some centers, particularly in ...
Common causes of polyostotic bone lesions in adults include:
arthritic or synovial-based lesions
non-ossifying fibromas (fibroxanthomas)
polyostotic fibrous dysplasia (McCune-Albright syndrome)
The differential diagnosis for a posterior mediastinal mass includes:
neurogenic tumors: most common
nerve sheath tumors
malignant peripheral nerve sheath tumor
parasympathetic ganglion tumors
Postobstructive pulmonary edema is a type of non-cardiogenic pulmonary edema and is an uncommon but well-described complication of upper airway obstruction.
It occurs in three clinical settings 6:
acute airway obstruction
chronic upper airway obstruction
Premature closure of a growth plate subsequently results in a shortened bone, which can occur in a number of situations.
juvenile chronic arthritis
juvenile rheumatoid arthritis
Proptosis (rare plural: proptoses) refers to forward protrusion of the globe with respect to the orbit. There are many causes of proptosis which can be divided according to location and it is worth remembering that it is not just orbital disease processes that cause proptosis.
Prostate cystic disease encompasses a wide variety of pathologies that all result in cyst formation within the prostate.
Prostatic cysts are common, and ~5-8% men will develop one 4,7. However they are much more common in patients being investigated for infertility, with one study...
Prostate peripheral zone T2 hypointensity is a common finding in pelvic MRIs that needs to be evaluated. A prostate MRI is usually performed with a multiparametric technique (mpMRI) to differentiate prostate cancer from more benign pathologies. mpMRI includes T2 weighted images, dynamic contrast...
Prostatomegaly is a term used to generally describe enlargement of the prostate gland from whatever cause. Usually, the prostate is considered enlarged on imaging when its volume measures beyond 30 cc (mL).
The term prostatomegaly is often used interchangeably with benign prostati...
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
Pseudobladder refers to a pelvic cystic mass that simulates the urinary bladder.
The location of the lesion should allow differentiation from the bladder but if doubt exists and clinical necessity arises, a delayed phase CT/MRI with excreted contrast or Foley catheter-administered retrograde co...
Pseudocirrhosis is a radiological term used to convey the imaging findings of cirrhosis, but emphasize that it occurs in the setting of hepatic metastases. It is most commonly reported following chemotherapeutic treatment of breast cancer metastases, although has also been reported before treatm...
Pseudohydronephrosis (plural: pseudohydronephroses) refers to normal anatomy or non-significant pathologies that may mimic hydronephrosis. There is usually fluid-density material within a dilated part of the urinary tract, but without other signs of obstruction such as retroperitoneal fat strand...
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...
Pulmonary arterial calcification is a phenomenon which is usually seen in the setting of advanced pulmonary hypertension. It can however be uncommonly present in those without pulmonary hypertension.
The general mechanism in the vast majority is thought to be from high end pulmonary ...
Pulmonary blebs are small subpleural thin-walled air-containing spaces, not larger than 1 or 2 cm in diameter (with the precise limit varying by source). Their walls are less than 1 mm thick. If they rupture, they allow air to escape into the pleural space resulting in a spontaneous pneumothorax...
Pulmonary calcification has many causes and varying morphology:
calcific pulmonary nodules or masses
healed varicella pneumonia
coal worker's pneumoconiosis
Pulmonary cavities are thick-walled abnormal gas-filled spaces within the lung. They are usually associated with a nodule, mass, or area of consolidation. A fluid level within the space may be present. Plain radiography and CT form the mainstay of imaging.
According to the Fleischn...
Pulmonary or interstitial fibrosis is a descriptive term given when there is an excess of fibrotic tissue in the lung. It can occur in a wide range of clinical settings and can be precipitated by a multitude of causes.
The term should not be confused with idiopathic pulmonary fibro...
Pulmonary fungal disease encompasses a broad spectrum of infections related to fungal sources. They can particularly affect immunocompromised individuals.
pulmonary aspergillosis: pulmonary aspergillus infection considered the most important in immunocompromised individuals 5
Pulmonary hemorrhage is a rather broad term given to describe any form of bleeding into the lung and can arise from a myriad of causes. In a very traditional sense it is described when the following constellation of clinicoradiological features occurs simultaneously 2 (although this is never an ...
Pulmonary hypertension has many causes, and these can be divided in many ways. A simple and systematic approach is to proceed along the cardiopulmonary pulmonary circulation, as causes are found at each site (for a more official classification system see 2003 third world symposium on pulmonary a...
Pulmonary infections are common and are caused by a wide range of organisms.
Micro-organisms responsible may enter the lung by three potential routes:
via the tracheobronchial tree
most commonly due to inhalation of droplets of secretions from another infected human
Pulmonary metastases are common and the result of metastatic spread from a variety of primary tumors via blood or lymphatics.
This article describes hematogenous pulmonary metastases with lymphangitis carcinomatosis discussed separately.
The epidemiology will match that of the un...
Pulmonary necrosis is seen in a variety of conditions, including 1:
Klebsiella pneumoniae - Klebsiella pneumonia
Haemophilus influenzae - pulmonary haemophilus influenzae infection
Pseudomonas aeruginosa - pulmonary pseudomonas aeruginosa infe...
Pulmonary nodules are small, rounded opacities within the pulmonary interstitium. Pulmonary nodules are common and, as the spatial resolution of CT scanners has increased, detection of smaller and smaller nodules has occurred, which are more often an incidental finding.
Pulmonary ossification is a rare finding and is characterized by the presence of mature bone in alveolar or interstitial spaces, either localized or disseminated throughout the lung parenchyma.
It can be idiopathic (idiopathic pulmonary ossification) or secondary to chronic lung, cardiac or sys...
Pulmonary vasculitis refers to vasculitides that affect the lung or pulmonary vessels. If this definition is used, a large group of conditions can fall into this category. The respiratory system may be potentially involved in all systemic vasculitides, although to a variable degree.
Pulsatile exophthalmos, a.k.a. pulsatile proptosis, is a clinical symptom characterized by protrusion - i.e. exophthalmos (proptosis) - and pulsation of the eyeball that can occur due to various causes:
neurofibromatosis type 1 (with sphenoid wing dysplasia) 2
Pure ground glass lung nodules are a subtype of ground glass lung nodules where there is no associated solid component.
They have been shown to represent various pathologies such as 1,3
adenocarcinoma in situ of lung
minimally-invasive adenocarcinoma of lung
Purely intrasellar pituitary masses have a similar differential as the more generic pituitary region mass gamut, or the mnemonic SATCHMO, although some entities are far more common than others.
Rathke cleft cyst
Pyelonephritis (plural: pyelonephritides) refers to an upper urinary (renal) tract infection with associated renal pelvis, renal calyceal and renal parenchymal inflammation, and comprises a heterogeneous group of conditions.
Pyometrium refers to infection of the endometrial cavity with resulting expansion due to accumulated pus (pyometra).
The postmenopausal demographic are most commonly affected due to the association with uterine malignancy.
endometritis / pelvic inflammatory disease
Rachitic rosary refers to expansion of the anterior rib ends at the costochondral junctions and is most frequently seen in rickets as nodularity at the costochondral junctions.
Other causes of this appearance include:
the costochondral junction is more angular ...
Complete fatty replacement of red marrow with fat on MRI can occur in a number of situations which includes:
regional radiation therapy
Reeder and Felson's Gamuts in Radiology, first published in 1975, provided comprehensive lists of radiological differential diagnoses, or gamuts, and was a bestseller for many years. The current publisher is Springer.
The first edition was edited and, primarily, written by Ben Felson and Mauric...
Regional osteopenia describes a localized or regional decrease in bone mineral density.
disuse osteopenia (usually aggressive osteoporosis with pseudopermeative pattern)
immobilization of fractures
bone and joint infections
complex regional pain syn...
Renal artery stenosis (RAS) (plural: stenoses) refers to a narrowing of a renal artery. When the process occurs slowly, it leads to secondary hypertension. Acute renal artery stenosis does not lead to hypersecretion of renin.
When the stenosis occurs slowly, collateral vessels form a...
Renal cortical defects have a variety of causes, and present on imaging as an area of focal cortical thinning or absence of renal cortex, sometimes accompanied by focal caliectasis.
The differential diagnosis for a renal cortical defect includes 1,2:
Renal emphysema, or intrarenal gas, refers to the presence of gas within the kidney, with or without extension to the urinary tract.It is a rare finding and only a few differentials need to be considered 1:
emphysematous pyelonephritis 1
A renal pseudotumor is a mass that will simulate a tumor on imaging but is composed of non-neoplastic tissue. There are many examples 1:
prominent column of Bertin
persistent fetal lobulation
cross-fused renal ectopia
renal hilar lip
Renal transplantation is one, if not the most, common transplant procedures undertaken worldwide. Consequently, purposeful and incidental imaging of renal transplants and renal transplant-related complications are increasingly common. These include acute renal transplant rejection and chronic re...
Renal vein varices develop for various reasons and are usually asymptomatic.
Renal vein varices are usually asymptomatic. Some patients may present with flank pain and/or hematuria.
chronic renal vein thrombosis