As is seen in this patient, the sphenoid sinus may extend beyond the body of the sphenoid bone to pneumatize or involve the adjacent regions. In this case, a lateral recess has been formed within the greater wing of the sphenoid sinus.
1 In general, there are three major types of anemia, classified according to the size of the red blood cells:  If the red blood cells are smaller than normal, this is called microcytic anemia. The major causes of this type are iron deficiency (low level iron) anemia and thalassemia (inherited disorders of hemoglobin).
Anemia is a lower than normal number of red blood cells (RBCs) in circulation. There are several different laboratory RBC measurements that can reveal anemia. Decreased RBC production, increased RBC destruction, and blood loss are the three major categories or causes of anemia.