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PA19.4 | Splenomegaly — Causes & Differentiation — SDL Guide (Part 4)

Clinical Approach to Differentiating the Cause

A four-panel medical infographic shows how spleen size, associated clinical features, and key investigations help differentiate causes of splenomegaly. — **Panel A:** Overview hub showing enlarged spleen in left upper abdomen and the three diagnostic axes: degree of enlargement, associated features, and key investigations.. **Panel B:** Spleen size comparison showing normal spleen, moderate splenomegaly, and massive splenomegaly with major causes including CML, myelofibrosis, kala-azar, malaria, thalassaemia major, and Gaucher/Niemann-Pick disease.. **Panel C:** Clinical clue map linking symptom clusters to likely causes: portal hypertension/cirrhosis, kala-azar, malaria, lymphoma/leukaemia, CML, myelofibrosis, Felty syndrome, thalassaemia major, and storage disorders.. **Panel D:** Investigation table showing FBC and film, LFTs and coagulation, BCR-ABL FISH/PCR, bone marrow biopsy, splenic aspirate or rK39 antigen test, and glucocerebrosidase assay with diagnostic values..

When you face splenomegaly, three axes guide differentiation:

1. Degree of enlargement (see block 5 table): massive splenomegaly narrows the list dramatically to the six diseases above.

2. Associated features:
• Jaundice + ascites + spider naevi → portal hypertension/cirrhosis (congestive)
• Fever + geography (Bihar) → kala-azar; fever + travel to malaria-endemic area → malaria
• Lymphadenopathy + B symptoms → lymphoma/leukaemia
• Leukocytosis + basophilia → CML; leukoerythroblastic film → myelofibrosis
• Joint disease + neutropenia → Felty syndrome
• Childhood onset + thalassaemic facies → thalassaemia major
• Bone pain + neuropathy → Gaucher/Niemann-Pick

3. Key investigations:

Test	Diagnostic value
FBC + film	Malaria parasites, spherocytes, target cells, basophilia, blast cells, leukoerythroblastic picture
LFTs + coagulation	Cirrhosis/portal hypertension
BCR-ABL (FISH/PCR)	CML
Bone marrow biopsy	Infiltration, storage disorder, fibrosis, hypercellularity in hypersplenism
Splenic aspirate / rK39 antigen test	Kala-azar
Glucocerebrosidase assay	Gaucher disease
Ultrasound abdomen + Doppler	Portal hypertension, vein thrombosis, texture

Effects of Splenectomy

Three-panel diagram comparing normal and post-splenectomy blood smears and summarizing OPSI risk from encapsulated bacteria with prevention strategies. — **Panel A:** Post-splenectomy peripheral blood smear showing Howell-Jolly bodies, target cells, thrombocytosis, acanthocytes, and Pappenheimer bodies with arrows.. **Panel B:** Normal peripheral blood smear showing regular RBCs without inclusions and normal platelet count.. **Panel C:** OPSI mechanism showing loss of IgM-mediated opsonisation, encapsulated bacteria risk, and prevention by vaccination, prophylactic antibiotics, and patient education..

Splenectomy removes filtration, immune, and reservoir functions. The haematological consequences appear on the blood film within days:

On blood film post-splenectomy:
• Howell-Jolly bodies (nuclear remnants in RBCs — normally pitted out) — pathognomonic of hyposplenic state.
• Target cells (codocytes) — excess cell membrane relative to volume after loss of pitting.
• Thrombocytosis — transient, peaks at 1–2 weeks; platelet count may reach 1,000 × 10⁹/L (thrombosis risk in reactive thrombocytosis).
• Acanthocytes (spur cells) — membrane lipid abnormality.
• Pappenheimer bodies (siderocytic granules).

Three-panel diagram showing post-splenectomy blood smear findings compared to normal blood, with associated infection risks and prevention strategies. — **Panel A:** Post-splenectomy blood smear showing Howell-Jolly bodies (nuclear remnants), target cells (bull's-eye RBCs), and thrombocytosis with annotated arrows. **Panel B:** Normal peripheral blood smear for comparison showing regular RBCs without inclusions and normal platelet count. **Panel C:** OPSI pathogens (S. pneumoniae, H. influenzae, N. meningitidis) and prevention strategies (vaccination, prophylactic antibiotics, patient education).

Infection risk — OPSI (Overwhelming Post-Splenectomy Infection):
The spleen produces IgM and opsonises encapsulated bacteria for Fc/complement-mediated phagocytosis. Loss exposes patients to:
• Streptococcus pneumoniae (commonest, most feared)
• Haemophilus influenzae type b
• Neisseria meningitidis

OPSI is a fulminant, often fatal septicaemia — mortality 50–70% once established. Prevention:
1. Vaccines: pneumococcal (PCV13/PPSV23), HiB, meningococcal — ideally 2 weeks before elective splenectomy.
2. Lifelong prophylactic phenoxymethylpenicillin (penicillin V) — especially in first 2 years and in children.
3. Patient education: fever → seek immediate medical attention.

SELF-CHECK

A 22-year-old with hereditary spherocytosis undergoes splenectomy. One week post-operatively, the blood film is reviewed. Which finding is MOST specific for the post-splenectomy state (as opposed to being present pre-operatively due to the haemolytic anaemia)?

A. Spherocytes

B. Polychromasia

C. Howell-Jolly bodies

D. Reticulocytosis

Reveal Answer

Answer: C. Howell-Jolly bodies

Howell-Jolly bodies (nuclear remnants in RBCs) are normally pitted out by the spleen. Their appearance on the film is pathognomonic of functional or anatomical asplenia — they are absent in HS before splenectomy. Spherocytes, polychromasia, and reticulocytosis are all pre-existing findings of haemolytic anaemia.