The Principles of Clinical Cytogenetics - Extra Materials - Springer

Cytogenetics of Solid Tumors 443
Fig. 9. Complex karyotype in a malignant germ cell tumor, including multiple copies of isochromosome 12p
(arrows).
for such assays stems from the fact that neoplastic cells shed from low-grade lesions are often impossible
to distinguish cytologically from non-neoplastic uroepithelial cells. Thus, FISH provides a useful
adjunct to cytology that can spare patients the discomfort of invasive biopsy procedures.
The diagnostic applications of FISH in bladder carcinoma might not be limited to follow-up of patients
with superficial carcinomas. Several bladder cancer risk groups can be identified based on environmental
and occupational exposures to carcinogens such as cyclophosphamide, tobacco, and various chemicals
used in synthesis of azo dyes and pigments (190–192). Individuals with chronic bladder infection by
Schistosoma haematobium are also at high risk for bladder cancer (193). Such infections are endemic in
Egypt, where bladder carcinoma is the most common malignant tumor, accounting for 20% of all cancers.
FISH might a useful diagnostic adjunct in these high-risk groups, particularly in patients with potential
signs or symptoms (e.g., unexplained hematuria) of bladder cancer.
BRAIN TUMORS
Distinctive cytogenetic aberrations are found in many of the major subtypes of brain tumor
(see Table 2), but karyotyping of brain tumors is not performed routinely in most cytogenetics