[Variant hairy-cell leukemia: immunophenotypic and ultrastructural study of a case]

The recent introduction of new methods to identify different lymphocytic subsets has made it possible to recognise a rare variant of the classic hairy cell leukaemia, showing intermediate features between prolymphocytic leukaemia and hairy cell leukaemia. A 37-year-old patient is reported who followed a mildly aggressive clinical course and had massive splenomegaly without lymph node enlargement. Moderate leucopenia with lymphocytosis was present, with frequent hairy cells carrying one prominent nucleole. The cytochemical pattern include tartrate-sensitive acid phosphatase positivity, and the immunophenotype of such cells was CD22++, CD11++, CD24-, CD25-, CD2-, CD5-, CD19++. No lamellar ribosomal complex was seen in the ultrastructural study of the hairy cells. The patient was diagnosed as having variant hairy cell leukaemia and achieved partial response after splenectomy. The clinical, diagnostic and therapeutic aspects of this rare variant are discussed.