Pathology Cheat Sheet
Empty Marrow, Full Consequences
Aplastic anaemia for NEET-PG: pancytopenia with fatty hypocellular marrow, immune stem cell destruction, Fanconi anaemia, and PNH with CD55 and CD59 loss.
MedNext Academy | 3 min read
Empty Marrow, Full Consequences
Aplastic anaemia for NEET-PG: pancytopenia with fatty hypocellular marrow, immune stem cell destruction, Fanconi anaemia, and PNH with CD55 and CD59 loss.
Aplastic anaemia as a syndrome of bone marrow failure, its causes, and the pancytopenia differential diagnosis.
High-yield lines
- Aplastic anaemia is pancytopenia with a hypocellular fatty bone marrow lacking abnormal infiltrate, fibrosis, or dysplasia.
- The fundamental defect is a quantitative reduction of pluripotent CD34-positive haematopoietic stem cells.
- Aplastic anaemia is a diagnosis of exclusion among the causes of pancytopenia.
- Most acquired aplastic anaemia is immune-mediated destruction of stem cells by cytotoxic T cells.
- Acquired causes include drugs such as chloramphenicol, benzene, radiation, and viral hepatitis.
- Inherited causes include Fanconi anaemia, dyskeratosis congenita, and Shwachman-Diamond syndrome.
- Fanconi anaemia is a DNA cross-link repair defect with congenital anomalies and cancer predisposition.
- The peripheral smear shows pancytopenia with a low reticulocyte count and no abnormal cells.
- The bone marrow biopsy shows markedly reduced cellularity replaced by fat.
- Aplastic anaemia can evolve to paroxysmal nocturnal haemoglobinuria or myelodysplastic syndrome.
- Paroxysmal nocturnal haemoglobinuria arises from a PIGA mutation causing loss of CD55 and CD59 with complement-mediated haemolysis.
- Severe aplastic anaemia is treated with allogeneic stem cell transplant or immunosuppression.
Mapped competency codes
- PA17.1
- PA17.2
Continue into the full chapter
This summary maps to PA17-aplastic-anemia.
Frequently Asked Questions
What defines aplastic anaemia?
Peripheral blood pancytopenia together with a hypocellular bone marrow replaced by fat, without abnormal infiltrate, fibrosis, or dysplasia.
What is the main mechanism of acquired aplastic anaemia?
Immune-mediated destruction of haematopoietic stem cells by cytotoxic T lymphocytes, often triggered by drugs, viruses, or toxins.
Which inherited disorder causes aplastic anaemia through DNA repair failure?
Fanconi anaemia, a defect in DNA cross-link repair associated with congenital anomalies and increased cancer risk.
What conditions can aplastic anaemia evolve into?
Paroxysmal nocturnal haemoglobinuria and myelodysplastic syndrome, reflecting an overlap of bone marrow failure states.
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