Page 206 - Textbook of Pathology, 6th Edition

190 are ingested by pigs or they infect vegetables. These eggs
then develop into larval stages in the host, spread by blood
to any site in the body and form cystic larvae termed
cysticercus cellulosae. Human beings may acquire infection
by the larval stage by eating undercooked pork (‘measly
pork’), by ingesting uncooked contaminated vegetables, and
sometimes, by autoinfection.

MORPHOLOGIC FEATURES. The cysticercus may be
SECTION I
single or there may be multiple cysticerci in the different
tissues of the body. The cysts may occur virtually
anywhere in body and accordingly produce symptoms;
most common sites are the brain, skeletal muscle and skin.
Cysticercus consists of a round to oval white cyst, about
1 cm in diameter, contains milky fluid and invaginated
scolex with birefringent hooklets. The cysticercus may
remain viable for a long time and incite no inflammation.
Figure 7.13 Microfilariae in blood film. But when the embryo dies, it produces granulomatous
reaction with eosinophils. Later, the lesion may become
scarred and calcified (Fig. 7.14).
haemoglobinuria, jaundice, pulmonary oedema, and acidosis
followed by congestive heart failure and hypotensive shock.
TORCH COMPLEX
FILARIASIS
Acronym ‘TORCH’ complex refers to development of
Wuchereria bancrofti and Brugia malayi are responsible for common complex of symptoms in infants due to infection
causing Bancroftian and Malayan filariasis in different with different microorganisms that include: Toxoplasma,
geographic regions. The lymphatic vessels inhabit the adult Others, Rubella, Cytomegalovirus, and Herpes simplex virus;
worm, especially in the lymph nodes, testis and epididymis. category of ‘Others’ refers to infections such as hepatitis B,
Microfilariae seen in the circulation are produced by the coxsackievirus B, mumps and poliovirus. The infection may
General Pathology and Basic Techniques
female worm (Fig. 7.13). Majority of infected patients remain be acquired by the foetus during intrauterine life, or
asymptomatic. Symptomatic cases may have two forms of perinatally and damage the foetus or infant. Since the
disease—an acute form and a chronic form. symptoms produced by TORCH group of organisms are
Acute form of filariasis presents with fever, lymphangitis, indistinguishable from each other, it is a common practice in
lymphadenitis, epididymo-orchitis, urticaria, eosinophilia a suspected pregnant mother or infant to test for all the four
and microfilariaemia. main TORCH agents.
Chronic form of filariasis is characterised by lymphadeno-
pathy, lymphoedema, hydrocele and elephantiasis.

MORPHOLOGIC FEATURES. The most significant
histologic changes are due to the presence of adult worms
in the lymphatic vessels causing lymphatic obstruction
and lymphoedema. The regional lymph nodes are
enlarged and their sinuses are distended with lymph. The
tissues surrounding the blocked lymphatics are infiltrated
by chronic inflammatory cell infiltrate consisting of
lymphocytes, histiocytes, plasma cells and eosinophils.
Chronicity of the process causes enormous thickening and
induration of the skin of legs and scrotum resembling the
hide of an elephant and hence the name elephantiasis.
Chylous ascites and chyluria may occur due to rupture of
the abdominal lymphatics.

CYSTICERCOSIS

Cysticercosis is infection by the larval stage of Taenia solium,
the pork tapeworm. The adult tapeworm resides in the Figure 7.14 Cysticercus in skeletal muscle. The worm is seen in
human intestines. The eggs are passed in human faeces which the cyst while the cyst wall shows palisade layer of histiocytes.