Immunohistochemistry has become a very important, and in some cases indispensable, tool in diagnostic pathology, enabling the precise identification of tumours, the detection of micrometastases in a given sample, and the evaluation of various
prognosis factors. However, in some cases, the use of multiple but distinct immunostains can lead to some unforeseen results-for example, the expression of an apparently aberrant marker by a neoplasm can sometimes be seen. In this context, we report our experience with a case of refractory anaemia with excess of blasts in transformation (RAEB-t) in which the blasts were unexpectedly found to express cytokeratin (CK).. An 86 year old woman with a past medical history of breast carcinoma treated by mastectomy and adjuvant radiotherapy was admitted to our institution because of worsening anaemia. The following haematological indices were noticed: haemoglobin, 8.6 g/litre;
erythrocytes, 2.5 × 1012/litre; white blood cells, 3 × 109/litre; and platelets, 465 × ...