Hairy cell leukaemia simplified

Hairy cell leukaemia is a chronic type of leukaemia caused due to neoplastic proliferation of mature B cells.

Hairy cell leukemia comic

As the comic and name suggests, leukemic cells have hair like cytoplasmic projections.

Important clinical findings:

• Splenomegaly (Often massive, is the most common and sometimes the only abnormal finding.)
• Hepatomegaly (Due to infiltration of the portal triads.)
• Absence of lymphadenopathy.
• Pancytopenia (Due to marrow failure and splenic sequestration.)
*sings* This place is too crowded, too many cool kids, uh uh, uh uh.. Who's Taylor Swift anyway, ew?
• Peripheral blood smear shows cluster of neoplastic cells with dense chromatin and bleb-like or hair-like cytoplasmic projections.
• These cells are positive for tartrate resistant acid phosphatase (TRAP) stain.
• Bone marrow is packed with leukemic cells.
• When you aspirate the bone marrow, tumour cells are frequently absent.

Interesting features about these findings:

• When splenomegaly due to neoplasm is seen, it is usually the white pulp which is infiltrated. But in hairy cell leukaemia it is preferentially the red pulp (beefy red spleen on gross examination) and the white pulp is obliterated.

• It is the only leukaemia without lymphadenopathy!

• Bone marrow aspiration doesn't show tumour cells because they are entrapped in the extracellular matrix composed of reticulin fibres.

• Hairy cells express surface IgH instead of the usual IgG.

Why express G when you can express your own initial? H for hairy! =P

Weird or not, I find hairy cells pretty cool and hip ;)

Mnemonic to some it all up:

I like to think of hairy cells as trapped in their own world.

They are TRAP stain positive. They are trapped in the red pulp. They are trapped in the bone marrow and that’s why you get a dry tap. They trapped everywhere else, therefore, they don’t show up in the lymph nodes and that’s why the clinical finding of lymphadenopathy is absent.

Treatment:

Hairy cell leukaemias give an excellent response to treatment.

Drugs of choice are purine nucleoside analogues, for example, 2-chloro-2 deoxyadenosine (2-CDA or cladribine) You do remember how important was the purine synthesis and degradation pathway from biochemistry, don’t you? 2-CDA is an adenosine deaminase inhibitor; adenosine accumulates to toxic levels in neoplastic B cells.

And to all those who are not leaving their place due to weird hair, get a haircut or something but just don’t get too malignant!

Be awesome & spread the immuno-love <3