Fluorescence in situ hybridization analysis of chromosome 12p in paraffin-embedded tissue is useful for establishing germ cell origin of metastatic tumors

Abstract

The over-representation of chromosome 12p sequences is crucial for the development of invasive testicular germ cell tumors. Testicular cancer patients may have metastatic tumors of diverse histologic types, including adenocarcinoma, undifferentiated carcinoma, sarcoma, or other malignancies that lack features of germ cell tumors. We sought to investigate the possible germ cell origin of such tumors using interphase fluorescence in situ hybridization. In all, 10 metastatic malignant somatic-type tumors from patients with histories of testicular cancer, as well as one malignant somatic-type tumor from a patient with primary mediastinal germ cell tumor were studied and included: adenocarcinoma (five cases), poorly differentiated carcinoma (one), sarcoma (four), and neuroendocrine carcinoma (one). The tumors were analyzed using fluorescence in situ hybridization using 12p spectrum green and 12 centromeric spectrum orange probes in paraffin sections. The patients ranged in age from 27 to 55 years (mean, 43). Colon and lung cancers from patients without germ cell tumors were used as controls. Adequate signals were observed in all tumors. Gain of chromosome 12p was seen in six tumors. None of the control tumors showed 12p amplification. Fluorescence in situ hybridization for 12p amplification in routinely processed surgical specimens is a useful adjuvant diagnostic tool in confirming the germ cell origin of metastatic tumors having the histologic appearance of somatic-type neoplasms.

Mixed germ cell sex cord–stromal tumors of the testis and ovary. Morphological, immunohistochemical, and molecular genetic study of seven cases

“…This genetic abnormality occurs in all primary sites and histologic types of all human germ cells tumors [4,17,201 with the exception of spermatocytic seminomas and prepubertal teratomas of the testis. Data suggest that the consistent gain of genetic material from chromosome 12 may be crucial for the development of an invasive germ cell tumor [29].…”

“…Each slide was independently enumerated by two observers (TV and RS). Tumors with a ratio of signals <1.5 as a mean per nucleus were interpreted as non-amplified, whereas cases exhibiting a ratio of signals ≥1.5 as a mean were classified as amplified ones [17]. In all cases, counting of germ cell nuclei population was performed.…”

Chromosome 12p abnormalities in dysgerminoma of the ovary: a FISH analysis

“…The quantitative criteria to determine 12p overrepresentation were previously described. 12 We analyzed the spatial distribution of the green and red signals to detect the specific patterns of signal aggregation consistent with i(12p), as previously reported. [13][14][15][16] A classical seminoma specimen was used as a positive control for FISH analyses, and lymphocytes in dysgerminoma specimens were used for the negative control.…”

“…[9][10][11][12] Sections (4 mm) were prepared from buffered, formalin-fixed, paraffin-embedded tissue blocks. The slides were deparaffinized with two washes of xylene, 15 mins for each, and the slides were subsequently washed twice with absolute ethanol, 10 min each.…”

Acquired cystic disease-associated renal tumors: an immunohistochemical and fluorescence in situ hybridization study

“…The slides were air dried and counterstained with 10 ml DAPI (Insitus, Albuquerque, NM, USA), covered with coverslips and sealed with nail polish. [21][22][23] The slides were examined using a Zeiss Axioplan 2 microscope (ZEISS, Gö ttingen, Germany) with the following filters: SP-100 DAPI, FITC MF-101 for Spectrum Green (CEP 6 and 10) and Gold 31003 for Spectrum Orange (CEP 1, 2, and 17) from Chroma (Chroma, Brattleboro, VT, USA). The images were acquired with a CCD camera and analyzed with MetaSystem Isis Software (MetaSystem, Belmont, MA, USA).…”