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Figure 15.23 Haemangioendothelioma nose. A, The vascular Figure 15.24 Haemangiopericytoma liver. Spindled cells surround
channels are lined by multiple layers of plump endothelial cells having the vascular lumina in a whorled fashion, highlighted by reticulin stain.
minimal mitotic activity obliterating the lumina. B, Reticulin stain shows These tumour cells have bland nuclei and few mitoses.
condensation of reticulin around the vessel wall but not between the
proliferating cells.
occurring most frequently in the skin, subcutaneous tissue,
liver, spleen, bone, lung and retroperitoneal tissues. It can
sized and large veins. Haemangioblastoma is the term used occur in both sexes and at any age. Hepatic angiosarcomas are
for similar tumour occurring in the cerebellum (Chapter 30). of special interest in view of their association with
carcinogens like polyvinyl chloride, arsenical pesticides and
Grossly, the tumour is usually well-defined, grey-red, radioactive contrast medium, thorotrast, used in the past.
polypoid mass.
Microscopically, there is active proliferation of endothelial Grossly, the tumours are usually bulky, pale grey-white,
SECTION III
cells forming several layers around the blood vessels so firm masses with poorly-defined margins. Areas of
that vascular lumina are difficult to identify. These cells haemorrhage, necrosis and central softening are frequently
may have variable mitotic activity. Reticulin stain present.
delineates the pattern of cell proliferation inner to the Microscopically, the tumours may be well-differentiated
basement membrane (Fig. 15.23).
masses of proliferating endothelial cells around well-
formed vascular channels, to poorly-differentiated lesions
C. MALIGNANT TUMOURS
composed of plump, anaplastic and pleomorphic cells in
Haemangiopericytoma solid clusters with poorly identifiable vascular channels
Haemangiopericytoma is an uncommon tumour arising from (Fig. 15.25).
pericytes. Pericytes are cells present external to the endo- These tumours invade locally and frequently have distant
thelial cells of capillaries and venules. This is a rare tumour
Systemic Pathology
that can occur at any site and at any age and may vary in metastases in the lungs and other organs. Lymphangiosarcoma
is a histologically similar tumour occurring in obstructive
size from 1 to 8 cm.
lymphoedema of long duration.
Microscopically, the tumour is composed of capillaries
surrounded by spindle-shaped pericytes outside the Kaposi’s Sarcoma
vascular basement membrane forming whorled Kaposi’s sarcoma is a malignant angiomatous tumour, first
arrangement. These tumour cells may have high mitotic
rate and areas of necrosis. Silver impregnation stain (i.e. described by Kaposi, Hungarian dermatologist, in 1872.
reticulin stain) is employed to confirm the presence of However, the tumour has attracted greater attention in the
pericytes outside the basement membrane of capillaries last two decades due to its frequent occurrence in patients
and to distinguish it from haemangioendothelioma with HIV/AIDS.
(Fig. 15.24).
CLASSIFICATION. Presently, four forms of Kaposi’s
Local recurrences are common and distant spread occurs sarcoma are described:
in about 20% of cases. 1. Classic (European) Kaposi’s sarcoma. This is the form
which was first described by Kaposi. It is more common in
Angiosarcoma
men over 60 years of age of Eastern European descent. The
Also known as haemangiosarcoma and malignant disease is slow growing and appears as multiple, small,
haemangioendothelioma, it is a malignant vascular tumour purple, dome-shaped nodules or plaques in the skin,