Malignant melanoma is a malignant neoplasm that arises from melanocytes (or cells that derive from melanocytes). Melanocytes predominantly occur in the basal layer of the epidermis and most melanomas, therefore, arise in the skin. However, melanocytes do occur in other locations and can give r...
Malignant pleural disease usually heralds a poor prognosis, whether it represents a primary pleural malignancy or metastatic involvement.
Clinical presentation is variable. Patients may be asymptomatic or have pleuritic pain. If associated with a sizeable pleural effusio...
A number of staging systems have been described for staging of malignant pleural mesothelioma. Below is the International Mesothelioma Interest Group TNM staging system.
T - Tumour
Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
Mucosa associated lymphoid tissue (MALT) lymphoma, also called extranodal marginal zone B-cell lymphoma, is a type of low-grade extranodal lymphoma.
MALT lymphoma represents ~7.5% of non-Hodgkin lymphomas. Average age of presentation is 60 years with a slight female predominance ...
Mandibular lesions are myriad and common. The presence of teeth results in lesions that are specific to the mandible (and maxilla) and a useful classification that defines them as odontogenic or non-odontogenic. While it may often not be possible to make a diagnosis on imaging alone, this classi...
Mantle cell lymphoma (MCL) is a type of non-Hodgkin lymphoma (NHL) and accounts for ~5% of all NHL. It is a malignant neoplasm of virgin B cells that closely resemble normal mantle zone B cells surrounding germinal centres.
They occur in older adults (mean age ~60 years). There is...
The Masaoka staging system is commonly adopted for thymomas 1-3, and is the most important determinant of survival following surgical resection 4:
stage I: intact thymic capsule
stage II: capsular invasion into adjacent mediastinal fat or pleura
stage III: macroscopic invasion into adjacent o...
Maxillary antral carcinomas are an uncommon head and neck malignancy. They usually present late despite growing large since they remain confined to the maxillary sinus and produce no symptoms.
Most commonly affects patients over 45 and has a strong male predilection (M:F = 5:1). M...
Metastases to the thymus are rare, although they are probably under reported due to lack of symptoms.
Varied primary tumours have been reported to metastasise to the thymus 1,2:
Metastases to the thyroid are an uncommon cause of thyroid malignancy.
Metastases to the thyroid represent 1.4-3% of all malignancies 5. In autopsy series, the incidence is ~10% (range 2-24%) 1,5.
The most common sites of primary malignancy include (note these will v...
Metastases to the vagina are more common than primary vaginal malignancies, and account for >80% of vaginal tumors.
Metastases usually spread from contiguous sites most commonly, with lymphatic and hematogenous metastases also recognised.
Tumors that metastasise to the vagina includ...
MRI protocols are a combination of various MRI sequences, designed to optimally assess a particular region of the body and/or pathological process.
There are some general principles of protocol design for each area. However, the specifics of a protocol are dependent on MRI hardware and software...
MRI reporting guidelines for cervical cancer help maintain uniformity of reports and assessment of important imaging staging criteria.
The tumour should be measured in three orthogonal planes. Tumours with a maximum diameter >4 cm are usually not amenable to primary radical surgery...
Multilocular cystic renal tumours (MCRT) are rare benign renal neoplasms occurring in a bimodal age distribution, involving young children and adults in the 4th and 5th decades.
For logical reasons, this article will discuss together the two ends of the spectrum of this disease, cystic partiall...
The differential diagnosis for multiple cystic neck lesions is different to that for a solitary cystic neck mass.
Cystic neck lesions are seen in:
necrotic metastatic SCC nodes: older patient, M>F
papillary thyroid carcinoma metastases: usually a younger patient, F>M
Multiple myeloma is the most common primary malignant bone neoplasm in adults. It arises from red marrow due to monoclonal proliferation of plasma cells and manifests in a wide range of radiographic abnormalities. Multiple myeloma remains incurable.
Four main patterns are recognise...
Muscle lymphoma is a rare manifestation of lymphoma.
Muscle lymphoma is rare, representing <2% of all lymphomas. Average age of presentation is 70 years 1.
Focal swelling and/or pain along with B-type symptoms 2. Any muscle can be ...
Musculoskeletal angiosarcomas, (along with haemangiopericytomas and haemangioendotheliomas) are tumours that arise from vascular structures. They are typically difficult to distinguish from one another on imaging alone.
Angiosarcomas, are the most aggressive of the three, frequently having meta...
Mycosis fungoides (MF), also known as cutaneous T-cell lymphoma, is a type of malignant T-cell lymphoma that primarily involves the skin.
In the United States, it is more common in males and African Americans. In Europe, it accounts for ~6% of all non-Hodgkin lymphomas. It is rar...
Myeloproliferative disorders (MPDs) are a diverse group of conditions that are characterised by the overproduction of red cells, white cells and/or platelets in bone marrow. There are numerous conditions considered in this group but the most common are:
Nasopharyngeal carcinomas (NPC) are the most common primary malignancy of the nasopharynx. It is of squamous cell origin, some types of which are strongly associated with the Epstein-Barr virus (EBV).
Nasopharyngeal carcinoma accounts for ~70% of all primary malignancies of the na...
Neonatal neuroblastoma is a type of congenital neuroblastoma, an embryonal tumour arising from the sympathetic nervous system. In the majority of cases (45%), the tumour is localised in the adrenal gland.
Neonatal neuroblastoma accounts for less than 5% of all cases and carries ...
Neoplasms of the spinal canal encompass a range of tumours which arise from or involve the spinal cord, theca and nerves.
These can be divided according to the tissue/structure of origin. Tumours of vertebral bodies are discussed separately: see vertebral body tumours.
Spinal cord ...
Nephroblastomatosis refers to diffuse or multifocal involvement of the kidneys with nephrogenic rests (persistent metanephric blastema).
Nephrogenic rest are found incidentally in 1% of infants.
Nephrogenic rests are foci of metanephric blastema that persist beyond 36 ...
There are two methods of neuroblastoma staging, one that is based on post-operative patients (INSS) and one developed for pre-treatment patients (INRGSS).
International Neuroblastoma Staging System (INSS)
This staging system is for post-operative patients and mainly for prognosis 1:
Nonbacterial thrombotic endocarditis (NBTE), also referred as marantic endocarditis, refers to fibrin and platelets aggregations on previously undamaged heart valves, in patients without bacteraemia. The condition is seen in patients with advanced stage malignancies, and is related to episodes o...
Ocular pathology covers a wide range of conditions and therefore represents the cause of a wide range of symptoms, signs and radiographic features.
Ocular metastases account for over 80% of all ocular pathology. With regard to the remainder of ocular lesions, the primary differentiating factor ...
Oesophageal cancer staging can depend slightly on whether the tumour is squamous cell or adenocarcinoma subtype. Due to the lack of a serosal layer, oesophageal cancer often tends to have mediastinal spread at the time of diagnosis.
Tx: primary tumour cannot be...
Oesophageal cancer is a relatively uncommon tumour that occurs within the oesophagus of affected individuals. Patients present with symptoms of increasing dysphagia that progress from solid foods to liquids.
This is a summary article; read more in our article on oesophageal c...
Oesophageal carcinoma is relatively uncommon. It tends to present with increasing dysphagia, initially to solids and progressing to liquids as the tumour increases in size, obstructing the lumen of the oesophagus.
Oesophageal cancer is responsible for <1% of all cancers and 4-10% ...
A mnemonic to remember the causes of an oesophageal mass is:
CALL the MVP
Oligometastases refers to distant disease that is limited in number and distribution, Niibe et al defined this as ≤5 metastatic/recurrent lesions with control of the primary lesion 1,2. These metastases can be treated with local measures (surgery, radiation therapy, etc) with the aim of increasi...
Omental cake refers to infiltration of the omental fat by material of soft-tissue density. The appearances refer to the contiguous omental mass simulating the top of a cake. Masses on the peritoneal surfaces and malignant ascites may also be present.
The most common cause is metasta...
Ommaya reservoir, also known as Ommaya shunt, is a device consisting of an intraventricular catheter connected to a reservoir (port) implanted beneath the scalp. It is used for intrathecal administration of medication such as chemotherapy (mainly in the treatment of meningeal lymphomas, but also...
Enlargement of the optic nerves is uncommon and has a surprisingly broad differential:
optic nerve glioma
optic nerve meningioma
Optic nerve meningiomas are benign tumours arising from the arachnoid cap cells of the optic nerve sheath, and represent ~20% of all orbital meningiomas, the majority of which are direct extensions from intracranial meningiomas.
These tumours typically appear as masses within the optic nerve, ...
Orbital pathology covers a variety of diverse diseases that affect the orbit. The complicating factor is that the orbit is composed of a large number of different tissues which each have a plethora of pathologies that can affect them.
For simplification, they can be separated i...
Osteopoikilosis is a sclerosing bony dysplasia characterised by multiple benign enostoses. It is a rare inherited benign condition incidentally found on skeletal x-rays. Its importance is predominantly in correct diagnosis so that it is not mistaken for pathology.
The bone islands...
The most commonly adopted ovarian cancer staging system is the FIGO staging system. The most recent staging system is from 2014 1:
CT is considered the best imaging modality for staging ovarian cancer. 4.
stage I: tumour limited to the ovary or fallopian tube
tumour limited to o...
Ovarian thecomas are benign ovarian tumours of sex cord / stromal (mesenchymal) origin. They are thought to account for approximately 0.5-1% of all ovarian tumours. As ovarian thecomas secrete oestrogen, they are described as functional ovarian tumours.
They typically present in o...
Ovarian transposition is a surgical procedure in which the ovaries are displaced from the pelvis before pelvic radiation therapy in order to protect them from radiation injury.
It is performed in premenopausal women with a variety of pelvic malignancies (e.g cervical cancer, rectal cancer, and ...
Paget disease of the breast, which is also known as Paget disease of the nipple, has traditionally been described as a form of breast malignancy characterised by infiltration of the nipple epidermis by malignant cells. Although most cases have underlying focus or foci of in situ or invasive carc...
Pancreatic calcifications can arise form many aetiologies.
Punctate intraductal calcifications
acute alcoholic pancreatitis (20-40%)
intraductal, numerous, small, irregular
preponderant cause of diffuse pancreatic intraductal calcification
idiopathic: no underlying ca...
Pancreatic ductal adenocarcinoma makes up the vast majority (~90%) of all pancreatic neoplasms and remains a disease with a very poor prognosis and high morbidity.
On imaging, it usually presents as a hypodense mass on CT that is poorly marginated, which may encase vessels and the common biliar...
Both endocrine and exocrine tumours of the pancreas are now staged by a single pancreatic staging system.
Staging of pancreatic ductal adenocarcinoma is with the TNM system, and as a majority of tumours are not-resectable, this is mostly achieved with imaging (typically CT scan) although laparo...
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...
Paraneoplastic syndromes occur secondary to the indirect effects of a malignancy and occur remotely to the primary malignancy. Symptoms are mediated by cytokines, hormones or immune cross-reactivity. These syndromes can cause a diverse range of symptoms and can affect multiple systems.
Parotid enlargement 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 causes.
Patellar tumours are extremely rare. They can be either benign or malignant primary bone tumours, or metastases.
Patellar tumours represent just 0.1% of all primary bone tumours 1.
Patients may present with anterior knee pain and/or a palpable mass 1,3.
A pedunculated intratracheal mass has a variety of differential diagnoses:
benign tumour, e.g. hamartoma, chrondroma, 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: 34%
pelvic malignancy: 14%
pelvic inflammatory disease: 8%
Extra-gynaecological masses, e.g. colorectal carcino...
Perineural spread of tumour is a form of local invasion in which primary tumours cells spread along the tissues of the nerve sheath. It is a well-recognised phenomenon in head and neck cancers.
An important distinction has to be made between perineural invasion (PNI) and Perineural spread (PNS...
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
Peritoneal mesothelioma is an uncommon primary tumour of the peritoneal lining. It shares epidemiological and pathological features with but is less common than its pleural counterpart, which is described in detail in the general article on mesothelioma. Other sub-types (also discussed separatel...
A mnemonic for permeative processes in bone is:
R: round cell tumours (Ewing sarcoma)
E: eosinophilic granuloma
M: metastases/myeloma/malignant fibrous histiocytoma
D: desmoid tumour
permeative process in bone
PET-CT is a combination of cross-sectional anatomic information provided by CT and the metabolic information provided by positron emission tomography (PET).
PET is most commonly performed with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG). F-18 is an unstable radioisotope and has a half-life of approx...
The pharyngeal (or superficial) mucosal space is one of the seven deep compartments of the head and neck. It consists of the mucosa and structures deep to the mucosa of the nasopharynx, the oropharynx, and the laryngopharynx.
The pharyngeal mucosal space is the most internal comp...
Pheochromocytomas are an uncommon tumour of the adrenal gland, with characteristic clinical, and to a lesser degree, imaging features. The tumours are said to follow a 10% rule:
~10% are extra-adrenal
~10% are bilateral
~10% are malignant
~10% are found in children
~10% are familial
Pineal cysts are common, usually asymptomatic, and typically found incidentally. Their importance is mainly in the fact that they cannot be distinguished from cystic tumours, especially when large or when atypical features are present. As such, many patients undergo prolonged follow-up for these...
Abnormal nodular enhancement of the pituitary stalk can be seen in:
granular cell tumour of the pituitary (a.k.a. pituitary choristoma)
pilocytic astrocytoma of the neurohypophysis (a.k.a. infundibuloma)
Post surgical breast scar is a benign complication that usually occurs following surgical intervention to breast tissue. It can however be a strong and potentially very confusing mimicker of breast malignancy.
Review of the patient's past history and previous mammography...
Primary benign cardiac tumours are much less common than secondary metastatic deposits. However they are more likely when a cardiac mass is seen outside of the setting of terminal metastatic disease. Tumours include 1-2:
most common in adults
accounts for ~50% of all primary be...
Primary bone (skeletal/osseous) lymphoma (PBL) is a less common manifestation of lymphoma than secondary involvement from disseminated lymphoma. It is rare, accounting for <5% of bone tumours and <1% of non-Hodgkin lymphoma.
PBL is defined as the presence of lymphoma isolated to on...
There are a number of primary malignancies of the nasopharynx:
nasopharyngeal carcinoma (squamous cell carcinoma): 70%
lymphoma (sinonasal lymphoma): 20%
adenoid cystic carcinoma
Primary mediastinal large B-cell lymphoma is a distinct entity, recognised in the WHO classification of lymphoma.
Primary mediastinal large B-cell lymphoma accounts approximately 5% of large B-cell lymphoma, which is usually disseminated or found in the abdomen. There appears to b...
Primary pleural lymphoma is extremely rare, especially in immunocompetent patients.
Primary pleural lymphoma accounts for <0.5% of all non-Hodgkin lymphoma 2 and ~2.5% of primary chest wall tumours 4.
Primary pleural lymphoma may be Hodgkin or non-Hodgkin lymphoma wit...
Primary pulmonary lymphoma (PPL) refers to a clonal lymphoid proliferation affecting the lungs without any detectable extrapulmonary involvement. It is a much rarer type of pulmonary lymphoma and is most frequently represented by lymphoma of B cell lineage - often marginal zone B-cell lymphoma o...
Primary urethral cancer staging often uses the TNM system and is as follows:
Primary tumour staging (T)
Tx: primary tumour cannot be assessed
T0: no evidence of primary tumour
Tis: carcinoma in situ
Ta: non-invasive papillary, polypoid, or verrucous carcinoma
T1: invasion of s...
Malignant uveal melanomas, also referred as choroidal melanomas, are the most common primary tumour of the adult eye 3.
Malignant melanoma of the uvea is the most common primary intraocular malignancy and is predominantly seen in Caucasians 5. The incidence of these tumours incre...
Prostate cancer staging can be thought of in terms of physical location or grading histologically. The TNM classification is used to determine spread, and the Gleason score is used to determine the histological type. Another staging system is the Jewett-Whitmore staging system.
Pseudo Meigs syndrome refers to a clinical syndrome of pleural effusion, ascites associated with an ovarian tumour that is not a fibroma or a fibroma-like tumour.
Entities that have been reported to result in pseudo Meigs syndrome include
colon carcinoma metastas...
Pseudomyxoma peritonei refers to the intraperitoneal accumulation of a gelatinous ascites secondary to rupture of a mucinous tumour. The most common cause is a ruptured mucinous tumour of the appendix/appendiceal mucocoele 10.
Occasionally, mucinous tumours of the colon, rectum, stomach, panc...
Pulmonary artery sarcomas are extremely rare tumours that originate from the intimal mesenchymal cells of the pulmonary artery. It is frequently misdiagnosed as pulmonary thromboembolism.
Primary malignant tumours of the pulmonary arteries are very rare with an incidence of 0.00...
Pulmonary lymphoma refers to lung parenchymal involvement with lymphoma.
It can be broadly divided as primary or secondary.
primary pulmonary lymphoma: (rare) usually non-Hodgkin lymphoma which is limited to the lung with or without mediastinal lymph node involvement and with no evidence of ex...
Pulmonary metastases are common and the result of metastatic spread from a variety of primary tumours via blood or lymphatics.
This article describes haematogenous pulmonary metastases with lymphangitis carcinomatosis discussed separately.
The epidemiology will match that of the ...
Pulmonary opacification represents the result of a decrease in the ratio of gas to soft tissue (blood, lung parenchyma and stroma) in the lung. When reviewing an area of increased attenuation (opacification) on a chest radiograph or CT it is vital to determine where the opacification is. The pat...
Radial scar, or complex sclerosing lesion, is a rosette-like proliferative breast lesion. It is not related to surgical scarring. Some authors, however, reserve the latter term to lesions over 1 cm 5.
It is an idiopathic process with sclerosing ductal hyperplasia.
Its significance is that it...
Radiation-induced lung cancers have been reported as a rare late complication of radiation therapy in both post-operative breast cancer and Hodgkin lymphoma patients. These occur 5-10 years (or later) after treatment 1-4. There appears to be increased risk of lung cancer in these patients if the...
Radiation-induced pulmonary fibrosis is the late manifestation of radiation-induced lung disease (RILD) and is relatively common following radiotherapy for chest wall or intrathoracic malignancies.
This article does not deal with changes seen in the acute phase. Please refer to the article on r...
Radiomics is a new emerging field of oncological medicine in which medical images are converted into multidimensional data by data-characterisation algorithms. The data is assessed for improved decision support. Radiomics has the potential to uncover disease characteristics that fail to be recog...
The appearance of multiple, well-defined lytic lesions (punched out lesions) of various size scattered throughout the skull constitutes the raindrop skull appearance of multiple myeloma. This term is applied as an analogy to rain hitting a surface and splashing, where it leaves a random pattern ...
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...
For both RECIST 1.0 and 1.1, the requirement for measurable disease at baseline depends on the endpoints of the clinical trial.
Fundamental concept common to both versions of RECIST: measurable lesions are those you CAN measure (determined at baseline). From these, select the target lesions as ...
Rectal cancer, although sharing many of the features of generic colorectal carcinoma (CRC), has some features that make it unique. These are predominantly related to its anatomical location which has implications in both preoperative imaging assessment and surgical technique.
Demographics and c...
Staging strongly influences the success of, and rate of local recurrence following rectal cancer resection. In rectal cancer, pre-treatment MRI is the evaluation of choice, guiding surgical and non-surgical management options.
See: TNM staging system for a general description.
Renal cell carcinoma staging using the TNM staging system for renal cell carcinoma. Older but still widely used system in some practices is the Robson staging system.
TNM staging (7th edition)
T1a: tumour confined to kidney, <4 cm
T1b: ltumour confined to kidney, >4 cm but <7 cm
Renal leiomyomas are benign tumours of the kidney originating from smooth muscle cells of the renal capsule, pelvis, calyces or blood vessels.
There is a 4-5.5% prevalence based on autopsy findings1.
Renal leiomyomas are usually incidental findings. In symptomatic cases,...
Renal oncocytoma is a relatively benign renal tumour. The main clinical importance of this lesion is the difficulty in pre-operatively distinguishing it from renal cell carcinomas, as epidemiology, presentation, imaging and even histology can be very similar.
Renal oncocytomas ac...
Renal osteodystrophy (ROD), also known as uraemic osteopathy, is the constellation of musculoskeletal abnormalities that occur in patients with chronic renal failure, due to concurrent and superimposed:
osteomalacia (adults) / rickets (children)
secondary hyperparathyroidism: abnormal calcium ...
Response evaluation criteria in solid tumours or RECIST refers to a set of published rules used to assess tumour burden in order to provide an objective assessment of response to therapy. They were initially introduced in 2000 and have undergone subsequent revision in 2009 (RECIST 1.1).
Rhabdomyosarcomas of the genitourinary tract are uncommon tumours occurring in pelvic organs. It is a disease nearly exclusive to the paediatric population.
For a general discussion of this type of tumour, please refer to the article on rhabdomyosarcomas.
The peak incidence of ...
Rhabdomyosarcomas of the biliary tract are rare tumours, usually identified in children, with a very poor prognosis. They are usually grouped under botryoid rhabdomyosarcomas.
For a general discussion of this type of tumour, please refer to the article on rhabdomyosarcomas.
Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterised by mental retardation, broad and often angulated thumbs and halluces, and distinctive facial features.
The estimated incidence is 1 in 100,000-125,000 live births 5.