Cytogenetic analysis of a hemosiderotic fibrolipomatous tumor.

Hemosiderotic fibrolipomatous tumor is an extremely rare, nonencapsulated, fatty lesion with a consistent histologic appearance that was originally considered reactive in nature. To our knowledge, there are no previous reports on the cytogenetics of this lesion. Reported here is a case of hemosiderotic fibrolipomatous tumor arising within the subcutaneous tissue of the right foot, dorsal aspect, of an otherwise healthy 35-year-old woman. Subsequent cytogenetic analysis revealed a clonal reciprocal translocation between chromosomes 1 and 10, with a further rearrangement involving this derivative chromosome 1 and chromosome 3. This, in addition to its characteristic morphology and immunophenotype, supports the neoplastic nature of this tumor and may aid in its diagnosis.

Evaluation of Her-2/neu status in carcinomas with amplified chromosome 17 centromere locus.

Accurate assessment of Her-2/neu (erb-b2) status in breast carcinoma is essential for therapy planning. Clinical assays are targeted at protein overexpression (immunohistochemical analysis) or gene amplification (fluorescence in situ hybridization [FISH]). Cases with aberrant FISH signal patterns are problematic and may lead to underreporting of Her-2/neu amplification. We performed FISH with additional chromosome 17 probes, SMS (Smith-Magenis syndrome critical region) and RARA (retinoic acid receptor), on 7 cases with unusual Her-2/CEP17 (chromosome 17 centromere control probe) results to assess whether different measurements of chromosome 17 copy number might clarify the Her-2/neu amplicon status. Although the Her-2/CEP17 ratio scores were within normal range (<2.0), the Her-2/SMS or Her-2/RARA ratio revealed amplification of Her-2/neu in 5 of 7 cases. Immunohistochemical analysis demonstrated Her-2/neu protein overexpression in the same 5 cases only. We describe novel application of SMS/RARA FISH probes for assessing cases with complex Her-2/CEP17 FISH patterns. Such additional data, correlated with immunohistochemical analysis, may help guide therapy in patients with breast carcinoma.

A New Rhesus Macaque Karyotype Based on Human-rhesus Synteny.

Rhesus macaque (Macaca mulatta), because of their similarity to humans, are often used to study complex neurobiology and anatomy, cardiovascular disease, and in vaccine development. While the rhesus genome is studied on its own by primatologists, the grand majority of rhesus macaque research is done with the intention of extrapolating the findings to human diseases and traits. As such, it makes sense that the rhesus genome and karyotype be arranged based on homology to human chromosomes in an effort to ease the comparisons between the two, and aide in interpreting data generated using rhesus macaque model systems. Various approaches have been utilized, including linkage analyses using radiation hybrid markers and human microsatellite loci, and next generation sequencing, to create a comprehensive rhesus genome. Here, we present for the first time, the rhesus macaque karyotype adjusted and renumbered to reflect human homology, and to complement the newly completed sequencing data.

ALK FISH Assays for Non-small Cell Lung Cancer Treatment Selection: Scoring Issues and Probe Design.

Lung cancer is becoming more treatable with new pharmaceuticals. There is a growing interest in FISH testing to determine which drugs to use on lung cancer patients for the best results, with a concurrent need for laboratories to provide ALK FISH testing for nonsmall-cell lung cancer. However, the test has some unique difficulties and requires a great deal of experience to interpret in some cases. A three-color probe may help make the ALK FISH test more reliable.

Meiotic exchange event within the stalk region of an inverted chromosome 22 results in a recombinant chromosome with duplication of the distal long arm.

Meiotic recombination occurs between homologous euchromatic regions of human chromosomes in early meiosis. However, such exchanges have been thought not to occur in the stalk regions of acrocentric chromosomes. We describe a child whose chromosome analysis suggests that crossovers do occur in homologous stalk regions. The proband, initially seen as a term female infant, was born to a 28-year-old mother. Dysmorphic features included wide metopic sutures, low anterior hairline, hypertelorism, external ear malformations, and cleft lip and palate. Blood chromosomes of the proband and parents were studied by G-banding, Q-banding, R-banding, and silver staining. The infant karyotype showed a sub-metacentric chromosome 22; that of the mother showed a pericentric inversion of chromosome 22. Chromosomes of the father were normal. In the infant, the abnormal chromosome 22 long arm appeared normal, but with additional long arm material attached to the distal short arm. In the mother, the distal long arm of the abnormal chromosome 22 was translocated to the distal short arm. The abnormal chromosome stalk in the child was intermediate in size to the stalk size of the abnormal and normal chromosomes 22 in the mother. Fluorescent in situ hybridization (FISH) analysis using chromosome 22 paint and ARSA gene probe confirmed that the duplicated material in the proband was of chromosome 22 origin; the karyotype interpretation is: 46,XX,rec(22)dup(22q)inv(22)(p13q13.1)mat. This abnormal karyotype is most likely due to a crossover event within the inversion loop during meiosis. The stalk length discrepancy suggests that the crossover site occurred in the stalk region.