A patient with Hb-6 gm%, TLC 1200, platelet-60,000, MCV-12 fl, what is the diagnosis?
The ﬁndings in the given question are: Anemia (Hb = 6 gm%), Reduced leukocyte count (TLC=1200), Reduced platelet count (60000), Reduced MCV (12 fL).
Normal value of MCV is 80-100 fL. It is the measure of size of RBC. Reduced MCV means microcytic and increased MCV means macrocytic RBCs. Normal TLC is 4000-11000, normal platelet count is 1,50,000 to 4,50,000 and normal Hb is above 12 g/dL.
Now, considering the options one by one:

Aplastic anemia has reduced RBC, WBC as well as platelet counts. Anemia is normocytic normochromic, thus it can be easily ruled out.
Paroxysmal nocturnal hemoglobinuria (PNH) typically presents with anemia which is usually normocytic normochromic.

If MCV is high, it is due to reticulocytosis. Neutropenia and thrombocytopenia may or may not be present.
Therefore, this option also cannot be the answer.

Megaloblastic anemia presents with raised MCV. There may be leukopenia as well as thrombocytopenia. Severity of these changes parallels the degree of anemia.
Myeloﬁbrosis usually presents with anemia, leukopenia and thrombocytopenia. Mostly anemia is normocytic but in 30% cases, microcytic anemia can be present.

Based on the above discussion, the most probable answer is ‘Myeloﬁbrosis’.
However, the value of MCV given is 12 fL which is practically not possible. Normal value of MCV is 80- 100 fL. MCV < 50 fL is considered to be extremely low. Therefore, one possibility is that it may be 112 fL and due to typographical error in the question, written as 12 fL. If this is the case, then the answer will become megaloblastic anemia.
Aplastic anemia
Megaloblastic anemia
PNH
Myelofibrosis