Neurogenic tumours
.pdfas the Hutchinson syndrome 2.
Rarely, neuroblastoma may present with a paraneoplastic syndrome (e.g. opsomyoclonus)5.
Other accompanying syndromes include
4.Pepper syndrome
5.blueberry muffin syndrome : multiple cutaneous lesions
Pathology
The tumours arise from the primitive neuroectodermal cells. The histology is similar to small round blue cell tumours 3.
Location
Neuroblastomas arise from the sympathetic nervous system 2-3 :
Intra abdominal occurrence is commoner than intra thoracic. Specific sites include
•adrenal glands : most common site of origin : 35%
•retroperitoneum : 30 - 35%
organ of Zuckerkandl coeliac axis
paravertebral sympathetic chain
•posterior mediastinum : 20%
•neck : 1 - 5%
•pelvis : 2 - 3%
Associations
The vast majority of neuroblastomas are sporadic, however in rare instances they may be associated with 1-4:
•Beckwith-Wiedemann syndrome
•central failure of ventilation
•DiGeorge syndrome
•Hirschsprung disease
•Neurofibromatosis type 1 (von
Recklinghausen disease)
Radiographic features
Plain film
Appearances are non-specific, typically demonstrating an intrathoracic or intrabdominal a soft-tissue mass. Pressure on adjacent bones may cause remodelling of ribs, vertebral bodies or pedicle thinning. Up to 30% may have evidence of calcification on the plain film.
Skeletally metastases are usually ill-defined and
lucent, with periosteal reaction or metaphyseal lucency. Sclerotic metastases are uncommon 2.
Ultrasound
Neuroblastoma on ultrasound demonstrates a heterogeneous mass with internal vascularity. Often there are areas of necrosis which appear as regions low echogenicity. Calcification may or may not be evident on ultrasound 2.
Nuclear medicine
A number of compounds are used for diagnosis and staging
•pentetreotide labeled to Indium-In111 (somatostatin analog)
not specific for neuroblastic tissue
•MIBG (metaiodobenzylguanidine labeled to Iodine-123)
95% of neuroblastomas secrete catecholamines, however
30% of neuroblastomas are negative on MIBG
sensitivity : 88%
specificity : 99% (for sympathetic tissue) 2 does not distinguish between
neuroblastoma, glanglioneuroblastoma, ganglioneuroma, carcinoid, and
pheochromocytoma Surveillance for metastatic recurrence
•Tc-99m MDP
◦36% of primary tumours negative
◦mainly to evaluate skeletal metastases
◦also able to detect some lung and liver
metastases 2
CT
On CT, the tumour typically is heterogeneous with calcifications seen in 80 - 90% of cases 2. Areas of necrosis are of low attenuation.
The morphology of is often most helpful, with the mass seen insinuating itself beneath the aorta and lifting it off the vertebral column. It tends to encase vessels and may lead to compression. Adjacent organs are usually displaced, although in more aggressive tumours direct invasion of the psoas muscle or kidney can be seen. In the latter it can make distinguishing neuroblastoma from Wilms tumour difficult (see neuroblastoma vs Wilms tumour).
Lymph node enlargement is often present.
MRI
MRI is superior to all other modalities in assessing the organ of origin, intracranial or intra-spinal disease and bone marrow disease 2.
•T1 : heterogeneous and iso to hypointense
•C+ (GAD) : variable and heterogeneous enhancement
•T2 :
◦heterogeneous and hyper intense
◦cystic / necrotic areas very high intensity
◦signal voids may be evident
Staging and metastatic disease
For staging refers to : neuroblastoma staging
Metastatic disease is common and has a variety of patterns.
•liver
diffuse infiltration (more common in stage 4S)
focal hypo-enhancing masses
•lung and pleura discrete nodules diffuse consolidation
pleural disease is uncommon
•brain and meninges
dural metastases can be diffuse of nodular brain metastases are uncommon but
variable in appearance
Treatment and prognosis
Treatment depends on the patients stage. Localised tumours considered to be 'low-risk' are surgically excised and patients tend to do very well (see below). In 'high-risk' tumours, a combination or surgery, chemotherapy +/- bone marrow transplantation is employed, unfortunately with poor overall results. In some cases, where tumours are very large, presurgical chemotherapy to attempt to downstage the tumour may be administered 2.
Patients with stage 1, 2 or 4S have a better prognosis. Unfortunately 40 - 60% of patients present with stage 3 or 4 disease 4. For advanced disease, the age of the child is most important 3.
•stage 1, 2 or 4S : 75 - 90% 3 year survival
•stage 3
◦< 1 year of age : 80 - 90% 1 year event free survival
◦> 1 year of age : 50% 3 year survival
•stage 4
◦< 1 year of age : 60 - 75% 1 year event free survival
◦> 1 year of age : 15% 3 year survival
Poor prognostic factors
•N-Myc mutation
•chromosome 1p deletion
•later age of onset
Better prognostic factors
• TRK-A expression
Differential diagnosis
For an intra-thoracic neuroblastoma consider
•intrathoracic lymphoma
•extra lobar pulmonary sequestration
•round pneumonia
•ganglioneuroma
•ganglioneuroblastoma
For an intra-abdominal neuroblastoma consider
•ganglioneuroma
•ganglioneuroblastoma
•rhabdomyosarcoma
•Wilms tumour
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Pheochromocytomas is 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 found in children
•~ 10% are familial
•~ 10 % are not associated with hypertension
Epidemiology
The majority of cases are sporadic. In ~ 5 - 10% of cases, a pheochromocytoma is a manifestation of an underlying condition including 1-4,6:
•MEN II (both MEN IIa and MEN IIb)
◦account for 3% of all pheochromocytomas
◦almost never extra-adrenal
◦almost always bilateral 4
•von Hippel-Lindau disease
• von Recklinghausen disease (neurofibromatosis type I)
•Sturge-Weber syndrome
•Carney triad : for extra adrenal pheochromocytoma
•tuberous sclerosis
•familial phaeochomocytoma
Clinical presentation
It is rare, but a classical cause of uncontrolled secondary hypertension. A minority of patients will manifest hypertensive crises. In addition to severe paroxysmal hypertension, patients may present with cardiac dysfunction (myocardial
infarction, pulmonary oedema) or neurological events (severe headache, visual disturbance, haemorrhagic strokes) 5.
The first investigation in cases where a pheochromocytoma is suspected is usually urinary catecholamines. When those results are positive then imaging is performed to try and localise the tumour.
Pathology |
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Pheochromocytomas |
are |
a type |
of paraganglioma. |
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Location |
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Adrenal
They most frequently arises from the chromaffin cells of the adrenal medulla.
Extra adrenal locations
Approximately 10% of all pheochromocytomas are not located in the adrenal glands. Extraadrenal tumours are more likely to be malignant and metastasise 4.
They can be found along the sympathetic chain
as well as in the urinary bladder and organ of Zuckerkandl. Thoracic paragangliomas are rare and only account for 1 - 2 % of all cases of pheochromocytoma.
Radiographic features
As a general rule tumours in the adrenal region tend to be large at presentation, usually larger than 3 cm, with an average size of ≈ 5 cm. When confined to the adrenal glands, and especially if suspected clinically the diagnosis is readily made. Small extra-adrenal tumours can however be a challenge to find. Overall 98% of tumours are in the abdomen, and 90% are confined to the adrenal glands 6.
It is also important to note that it is not possible to distinguish malignant from benign pheochromocytomas merely on the direct appearance of the mass. Rather, the distinction is made on demonstrating evidence of direct tumour invasion into adjacent organs / structures or the presence of metastases 4.
CT
CT is the first imaging modality to be used, with an overall sensitivity of 89%. This is on account of 98% of tumours being located within