Spleen - Pathology

()Map LYMPHORETICULAR & HAEMATOPOIETIC SYSTEM (Map) SECONDARY LYMPHOID SYSTEM

NB:Be aware of age-related changes regarding the spleen

Anatomy & Physiology

See here

Splenic Lesions

• splenomegaly is the main clinical finding associated with the spleen in disease

Chronic Venous Congestion

• this may be seen along with chronic venous congestion of the liver in cases of chronic cardiac failure

Barbituates

• administration of barbituates can produce a degree of splenomegaly due to splenic engorgement by erythrocytes

Splenic Tumours

• these are important surgically since splenomegaly can be diagnoses clinically by palpation or X-ray and some are surgically curable

Hyperplastic Nodules or Benign Lymphoma

• very common incidental findings in older dogs
• should not be mistakenly identified as pathognomic lesions
• consist of nodules of hyperplastic white and red pulp

- usually 1-2 cms in size, but occasionally may be larger

- spherical

- protrude hemispherically from the surface as yellow and red mottled nodules

• infrequently, may rupture and give rise to haemorrhage

Haemangioma

• benign tumour of dogs
• may grow to considerable size

- the size of the lesion giving rise to clinical signs is compounded by haemorrhage from and into the tumour

- thus, a large mass of apple size may be found protruding from the spleen and adherent to the omentum

• on section, it is largely blood clot
• responds well to surgery

- therefore it must be distinguished from haemangiosarcoma

Haemangiosarcoma

• highly malignant tumour of dogs
• distinguished from the superficially similar haemangioma by the presence of much more formed, solid tumour tissue
• accurate prognosis demands histological examination
• secondaries are common locally in the omentum and in the liver

- course is usually short, often only a month or two

- metastases may occur in almost every organ

Haematopoietic Neoplasms

lymphosarcoma

• splenomegaly occurs in multicentric lymphosarcoma
• splenic enlargement may be marked if any form of lymphosarcoma is in leukaemic phase

myeloid (granulocytic) leukaemia

• rare
• all species
• extreme form with spleen approaching liver size

systemic mastocytosis

• cat
• extreme form with spleen approaching liver size