Pheochromocytoma

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Clinical features

Known as “10% tumour”: 10% bilateral; 10% extra-adrenal; 10% malignant; and 10% in children.
Peak age is the fifth decade
90% are sporadic and 10% have a familial history of multiple endocrine tumours (MEN syndromes)
Frequent clinical manifestations: paroxysmal hypertension, headaches, nausea, vomiting, diaphoresis, palpitations, tremors, fatigue, anxiety, chest and abdominal pain and visual disturbances.
Children are more affected with clinical symptoms than adults are; 90% suffer from hypertension, convulsions, polydipsia or polyuria
Bilateral cases are more frequent in children
Secretion of norepinephrine and epinephrine; rare cases with production of ACTH or VIP

Cytopathology

Hypercellular smears, with single cells and loose clusters
Variation in cell size or shape
Nuclear pseudo inclusions
Granular cytoplasm with frayed borders
Poorly defined reddish granular cytoplasm (Giemsa stain)

Immunocytochemistry

Neurofilaments: positive
Vimentin: positive
Chromogranin: positive
Synaptophysin: positive
CD56 N-CAM: positive
NSE: positive
S-100 protein: positive in sustentacular cells
Cytokeratin: controversial; sparse when present
EMA: negative
Alpha-inhibin: generally negative
Indicators of malignancy
- p53: positive
- Ki-67: positive

Genetic studies

10% of sporadic pheochromocytomas harbour somatic mutations involving proto-oncogene
MEN 2a and 2b are associated with the chromosome 10q11.2-ret proto-oncogene site

Differential diagnosis

Sarcomatoid renal cell carcinoma
- Cytokeratin’s are generally intensely positive
Adrenocortical carcinoma
- Bcl-2: positive
- Inhibin A: positive
- Chromogranin: negative
- EMA: positive

Main points

Malignant pheochromocytomas are slow-growing neoplasms: five-year survival rate of 40-50%
Common sites for metastasis: lymph nodes, bone and liver
Mutations of the neurofibromin gene seem to contribute to the development of pheochromocytomas in patients with Von-Recklinghausen’s disease