Cytogenetic abnormalities precede morphological abnormalities in developing malignant conditions: report of 2 cases.

We previously hypothesized that cytogenetic abnormalities precede morphological abnormalities in developing malignant conditions. In this context we evaluated additional cases to further confirm that hypothesis. We report on 2 additional cases in which clonal cytogenetic abnormalities were observed in otherwise morphologically normal samples. Case 1 is a bone marrow from a 73 year old male with transformed follicular lymphoma (FL), while case 2 is a lymph node from a 53-year-old with lymphadenopathy, both referred to the cytogenetics laboratory for evaluation. A 73-year-old male presented with an enlarging left inguinal mass surrounding and obliterating the left iliac vein. A tissue core biopsy of the mass revealed recurrent high grade FL with diffuse large B-cell lymphoma (DLBCL). Examination of a random bone marrow biopsy of the adjacent left posterior iliac crest showed only mild hypercellularity (50%) and no evidence of malignancy, and the results were confirmed by flow cytometry. Cytogenetic evaluation revealed an interstitial deletion, del (9)(q13q32). In case 2, morphologically the lymph node showed extensive paracortical hyperplasia with numerous eosinophils and no clear indication of a neoplastic process with no abnormal lymphoid population observed by flow. PCR studies for TCR gamma and IgH gene rearrangements were negative for clonality. Chromosome analysis demonstrated 47,XY,+add(1)(p22),t(3;14)(q27;q11.2)[13]/46,XY[7]. FISH studies showed a BCL6 gene rearrangement but no TCRAD rearrangement. A subsequent inguinal lymph node biopsy showed DLBCL. These cases along with the other cases in the literature provide further evidence of genetic abnormalities preceding morphological abnormalities in developing malignant conditions.