[Acquired aplastic anemia: a stereological analysis of bone marrow fatty tissue and its clinical correlations].

Background: To analyze the changes of the number and size of bone marrow adipocytes in aplastic anaemia. To discover possible clinical and haematological factors which may be associated with predominant expansion of the number or size of adipocytes. To analyze the prognostic value of the adipocyte number and size.

Methods: The adipose tissue of 25 plastic-embedded bone marrow specimens corresponding to patients with aplastic anaemia was studied stereologically. The correlation study between the results obtained and clinical and haematological data was carried out.

Results: The expansion of the adipose tissue is due to the predominant increase of the adipocyte number in some cases and of the adipocyte size in others. Among different clinical and haematological factors, only a lower age is significantly associated with a predominant increase of adipocyte number. In the prognostic stratification performed according to three different systems, neither the adipocyte number nor the size showed a statistically significant association.

Conclusions: In the aplastic anaemia, the younger patients expand their bone marrow adipose tissue by increasing predominantly the adipocyte number, whereas in the older patients this occurs by predominantly increasing the adipocyte size (may be due to the decrease in proliferative potential). On the other hand, both the adipocyte number and size lack prognostic significance.