Juxtaglomerular cell tumour (JGCT) is an infrequent renal tumour of the juxtaglomerular cells. These cells secrete renin and often cause severe hypertension and hypokalaemia.
Juxtaglomerular cell tumour affects all age groups, but is most common in adolescents and young adults, wi...
Kimura disease is a rare benign inflammatory disease that characteristically manifests as enlargement of cervical lymph nodes and salivary glands.
Kimura disease typically affects males (80%) between 20 and 40 years of age (80% of cases) 1-2, and is most frequently seen in Asia. S...
The Krenning score is a proposed semi-quantitative method of assessing the degree of tracer uptake on octreotide scintigraphy.
Initially designed for assessment of 111In-DTPA on planar imaging, the Krenning score is applicable to SPECT or SPECT/CT using various radiopharmaceuticals....
Lambert-Eaton myasthenia syndrome (LEMS) is rare but is still the second most common neuromuscular junction disease after myasthenia gravis. Two-thirds of LEMS present as a paraneoplastic syndrome secondary to malignancy, most commonly lung cancer but is also associated with breast, ovarian and ...
The skeleton is the most commonly involved organ system in Langerhans cell histiocytosis (LCH) and is by far the most common location for single-lesion LCH, often referred to as eosinophilic granuloma (EG) (the terms are used interchangeably in this article). For a general discussion of this dis...
Large cell carcinoma of the lung is one of the histological types of non-small cell carcinomas of the lung.
It is thought to account for approximately 10% of bronchogenic carcinoma 1.
Patients present with dyspnea, chronic cough and haemoptysis.
Large cell neuroendocrine carcinoma (LCNEC) of the lung is classified as a subtype of large cell carcinoma of the lung. It is also classified as a pulmonary neuroendocrine tumour.
The incidence peaks around the sixth decade 6. There is an increased male predilection 7.
Laryngeal squamous cell carcinoma staging uses the TNM staging system and actual staging is subsite (see laryngeal subsites) specific for T1-3. A rough approximation for all subsites is
T1: limited to one subsite and normal cord mobility
T2: more than one subsite and impaired cord mobility (bu...
Leiomyosarcomas (LMS) are extremely rare malignant neoplasms that originate from smooth muscle cells and may be considered the malignant counterpart of a leiomyoma. They are classified as a soft tissue tumour and account for ~8% of malignant soft tissue tumours 10.
Leptomeningeal enhancement refers to a diffuse or focal gyriform or serpentine enhancement that can be seen in the following conditions:
tuberculous meningitis (can also be focal)
CNS cryptococcal infection
coccidioidal meningitis (c...
Littoral cell angioma of the spleen (LCA) is a rare and relatively recently (1991) described vascular tumour of the spleen.
Littoral cell angiomas may occur at any age and have no gender predilection.
Typically, patients with littoral cell angioma are found...
Lobular breast carcinoma is a subtype of breast cancer can range from lobular carcinoma in situ (LCIS) to invasive lobular carcinoma.
Multicentricity and bilaterality tend to be quite common with lobular breast carcinomas.
Lobular carcinoma in situ (LCIS) represents the next step up from atypical lobular hyperplasia (ALH) along the malignant spectrum of lobular breast carcinoma.
LCIS occurs predominantly in premenopausal women with a mean age of 45 years old, approximately 10-15 years younger than t...
Low-grade appendiceal mucinous neoplasms (LAMN), previously known as appendiceal mucinous cystadenomas, are rare mucinous tumours of the appendix showing low-grade cytologic atypia, c.f. high-grade appendiceal mucinous neoplasms.
Considerable controversy still exists on mucinous n...
Mnemonics for the differential diagnosis of lucent/lytic bone lesions include:
They are anagrams of each other and therefore include the same components. They are by no means exhaustive lists, but are a good start for remembering a differential for a lucent/lytic bone...
The Lugano classification recommends two methods of visualization for standing lymphoma:
Computer tomography (CT)
Positron emission tomography–computed tomography (PET/CT)
Response Assessment on CT
CT uses for the standing of all types of lymphoma (if CT is performed for tumor size measure...
Lung cancer, or frequently, if somewhat incorrectly, known as bronchogenic carcinoma, is the most common cause of cancer in men, and the 6th most frequent cancer in women worldwide. It is the leading cause of cancer mortality worldwide in both men and women and accounts for approximately 20% of ...
Lung carcinomas of the salivary gland type are also known as salivary gland–type tumours of the lung (SGTTLs) or bronchial gland neoplasms.
The usual consignation to the group of non-small cell lung cancer (NSCLC) may be unfortunate because the clinical behavior of SGTTLs can be quite differen...
Lymphangitic carcinomatosis, or lymphangitis carcinomatosa, is the term given to tumour spread through the lymphatics of the lung and is most commonly seen secondary to adenocarcinoma.
The demographics will reflect that of the underlying malignancy (see below).
Lymphoma is a malignancy arising from lymphocytes or lymphoblasts. Lymphoma can be restricted to the lymphatic system or can arise as extranodal disease. This, along with variable aggressiveness results in a diverse imaging appearance.
Lymphoma accounts for ~4% of all cancers 4. T...
Lymphoma of the spinal cord is an uncommon manifestation of lymphoma. Although lymphoma more commonly involves the vertebral body (vertebral body tumours) or epidural compartment, intramedullary lymphoma may rarely occur.
Apparent intramedullary spinal cord lymphoma may often, in fact, repres...
Lymphoma of the uterine cervix is generally uncommon and when it does occur tends to present as cervical involvement with added background multi-organ disease rather than isolated primary cervical lymphoma 1. It is often considered part of the spectrum of uterine lymphoma.
In the ...
There are a number of lymphoma staging systems for both Hodgkin lymphoma and non-Hodgkin lymphoma including the Ann Arbor classification, Cotswolds-modified Ann Arbor classification, and the most current, Lugano classification.
Evolution of lymphoma staging and treatment response evaluation cr...
Lymphomatoid granulomatosis of the central nervous system is uncommon, but represents the second most common site of involvement in patients with systemic lymphomatoid granulomatosis, after the lungs, which are most commonly involved. It is considered one of the immunodeficiency-associated CNS l...
Male breast disease includes a wide spectrum of conditions. Many conditions and entities that affect the female breast may also affect the male breast.
male breast cancer
pseudogynaecomastia - fat deposition within th...
Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative.
This is a summary article; we do not have a more in-depth reference...
Malignant fibrous histiocytoma (MFH), which has more recently been classified as pleomorphic undifferentiated sarcoma (PUS) and formerly known as fibrosarcoma, is considered the most common type of soft tissue sarcoma. It has an aggressive biological behaviour and a poor prognosis.
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. The average age of presentation is 60 years with a slight female predomina...
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...
Meningeal melanocytomas are rare benign primary melanocytic tumours of the CNS that are derived from leptomeningeal melanocytes. They can occur anywhere along the neuraxis but are most commonly found in the spinal canal near the foramen magnum, as well as the posterior fossa, Meckel’s cave, or a...
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 tumours.
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. The average age of presentation is 70 years 1.
Focal swelling and/or pain along with B-type symptoms 2. Any muscle can be involved but most comm...
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:
Myoinositol is one of the compounds images with MR spectroscopy (MRS) at both 1.5 T and 3 T and is seen to resonate at 3.5 ppm chemical shift (right of the choline peak).
Myoinositol is a precursor of both phosphatidylinositol (the major inositol-containing phospholipid) and of phosphatidylino...
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 carrie...
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 of...
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 increa...
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...
Staging of pancreatic ductal adenocarcinoma is traditionally done according to American Joint Committee on Cancer (AJCC) / Union for International Cancer Control (IUCC) TNM system. As of 2010 (7th edition AJCC), both exocrine and endocrine tumours of the pancreas are now staged using the same s...
Pancreatic lymphoma is most commonly a B-cell sub-type of non-Hodgkin lymphoma.
Typically seen in middle-aged patients: mean of 55 years; range, 35-75 years and in immunocompromised patients.
Presentation is often non-specific. reported symptoms include 1:
Pancreatic mesenchymal neoplasms (or pancreatic nonepithelial neoplasms) are a group of rare pancreatic neoplasms that arise from the structural elements of the pancreas (nerves, fat, lymph), rather than from the exocrine or endocrine cells of the pancreas. Neoplasms from exocrine and endocrine ...
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...
Pancreatoblastomas are rare paediatric tumours of the pancreas. However, they are the most common pancreatic neoplasm of childhood and are often associated with a raised alpha-fetoprotein.
There is slight male predilection. Usually occurs in the first decade of life with a mean ag...
Papillary carcinoma of the breast is a rare ductal breast malignancy.
They are thought to account for 1-2% of breast carcinomas 2. They typically present in postmenopausal patients with the mean age at being ~63-67 years.
A papillary carcinoma may manifest ...
Papillary meningiomas (PM) are a rare subtype of malignant (WHO grade III) meningiomas that tends to occur in young patients and are characterised by an aggressive growth pattern illustrated by atypical imaging features such as brain and bone invasion. These tumours have a strong tendency of rec...
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...
Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST) make use of positron emission tomography (PET) to provide functional information to help determine tumor viability.
The criteria consist of four categories: complete metabolic response, partial metabolic response, progress...
Pericardial mesothelioma refers to a mesothelioma arising primarily from the pericardium.
They are rare and are only thought to account for ~0.7% of all malignant mesotheliomas. There is male to female predominance of approximately 3:1.
The presentation of...
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 perineura...
Periosteal osteosarcoma is a form of surface osteosarcoma.
It is the second most common type of juxtacortical or surface osteosarcoma after parosteal osteosarcoma and accounts for 1.5% of all osteosarcoma cases. It affects a slightly older age group (10-20 years) cf. conventional...
Peripheral pulmonary carcinoid tumour refer to a subtype of pulmonary carcinoid tumours that arise within the periphery of the lung. They are considered less common than the more centrally-located bronchial carcinoid tumours.
Many patients tend to be asymptomatic 2. Pre...
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 subtypes (also discussed separately...
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