Hodgkin’s disease is a unique cancer in many regards but it is classified amongst the lymphomas.
The histological/microscopical picture in Hodgkin’s disease is that of a mixture of cells. The malignant cell itself is probably the so-called Sternberg-Reed (RS) cell (which probably originated from the lymphocyte lineage - the malignant clonal origin of the RS cell has only recently been confirmed by PCR analysis) but this cell type may only comprise 1% of the total cellular picture in the material called Hodgkin’s disease and indeed there may only be variants of the classic Sternberg-Reed cell (which has two nuclei and is a large cell with an unmistakable microscopic picture) or even no typical examples in a biopsy specimen, making diagnosis a challenge.
In the rest of the background material of a microscopic specimen of Hodgkin's disease tissue, is a mixture of lymphocytes, eosinophils, plasma cells, granulocytes and histiocytes, such that most ‘white cell' lineage cells are represented. How much these other cell populations are only reactive and whether the Sternberg-Reed cell is the only malignant cell is still discussed, but what every histologist agrees is that Sternberg-Reed cells or their variants must be present in any biopsy for it to qualify for the diagnosis of Hodgkin’s disease.
Having said the above, there are four classic types of Hodgkin’s disease recognised down the microscope: the first is the lymphocyte predominant type, where, as the name suggests, the lymphocyte is the dominant cell – this has the best prognostic outlook for the future but is relatively uncommon (less than 5%).
The second is called nodular sclerosing Hodgkin’s disease because microscopically there are well-defined microscopic nodules demarcated by sclerosing/fibrous strands. This sub-type of Hodgkin’s also has a good outlook and is common; approximately 70% of patients in the UK have nodular sclerosing disease and it is disproportionately common in females.
The third variety of Hodgkin’s disease is called mixed cellularity and is more commonly found in the Middle East and Asia and carries a worse prognosis unless treated aggressively; it only accounts for 20% in the UK. The typical histological features are the commoner occurrence of Sternberg-Reed cells and their variants in a background of mixed cell types and no sclerosis.
The worst type of Hodgkin’s disease to suffer is lymphocyte depleted where the Sternberg-Reed cells predominate and the lymphocytes are hard to come by and there is not a lot of reactive background. Fortunately, only 5% of the disease is of this variety, as it is the most aggressive type of the disease.