Page 344 - Concise Pathology for Exam Preparation ( PDFDrive )

12 Haematology 329

3. Blast crisis phase of CML: This phase represents the transformation of CML into an
acute leukaemia.
(a) ‘Myeloid blast’ crises (70%) when the disease transforms into acute myeloblastic
leukaemia.
(b) ‘Lymphoid blast’ crises (30%) when the disease transforms into acute lymphoblas-
tic leukaemia.
Blast crisis is characterized by
• Sudden increase in splenic size
• Anaemia and thrombocytopenia
• Generalized lymphadenopathy
• Peripheral smear and bone marrow showing numerous blast cells (. 20%) simulating
acute leukaemia
• Refractoriness to treatment (treatment of blast crisis is as for acute myeloblastic or lym-
phoblastic leukaemia)

Q. Outline the clinical features and laboratory diagnosis of primary
myelofibrosis (agnogenic myeloid metaplasia).

Ans. Myelofibrosis is a clonal myeloproliferative disorder characterized by increased
fibrosis within the marrow, splenomegaly and extramedullary haemopoiesis in the spleen,
liver and at times, in lymph nodes, kidneys and adrenals.

Clinical Features
It is commonly seen between 40 and 70 years manifests with:
• Symptoms of anaemia like lassitude, fatigue, weakness and anorexia
• Symptoms due to massive splenomegaly like abdominal distension, dyspnoea and
dragging discomfort in the left hypochondrium
• Symptoms resulting from hypermetabolic state like fever, weight loss, sweating and
heat intolerance
• In late stages, bleeding tendencies occur due to thrombocytopenia.
• Hepatomegaly with portal hypertension and oesophageal varices, lymphadenopathy,
ascites, cardiac failure and jaundice also seen

Laboratory Diagnosis
• Typical picture is leukoerythroblastic (simultaneous presence of erythroid and granu-
locytic precursors in the peripheral blood). There is marked anisopoikilocytosis. RBCs
are usually normocytic normochromic with the presence of a fair number of tear-drop
poikilocytes and oval/elliptical cells. Polychromatophils and basophilic stippling may
also be seen.
• Platelet count is increased in the early stages, but decreased in the late stages.
• Total leukocyte count may be normal, increased (early stages) or decreased (late stages).
Myeloid precursors are abundant but blasts do not exceed 10%.
• Bone marrow examination
• Early stage or ‘cellular phase’: The marrow is hypercellular with an increase in all
three cell lines, particularly megakaryocytes. Fibrosis is minimal.
• Late stage or ‘hypocellular phase’: The marrow is hypocellular with reduction in all
cell lines. Marked increase in fibrosis.
• Leukocyte alkaline phosphatase (LAP) score is elevated.
• Philadelphia chromosome is negative.

Q. Differentiate between CML and myelofibrosis.

Ans. Contrasting features of CML and myelofibrosis are listed in Table 12.16.

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