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Clinical Profile | Diagnosis | Treatment | Discussion

CLINICAL PROFILE:

A 65-year-old lady presented with a dull aching pain and gradually increasing lump in the right hypochondrium and epigastric region over three months. Anorexia and weight loss were associated complaints. There was no jaundice, bowel or bladder complaints.

On abdominal examination multiple small, firm, nodular swellings were noted in the epigastric region. Another well defined, firm, 10 cm sized swelling was noted in the right hypochondrium. This showed minimal movement with respiration.

Routine blood investigation showed eosinophillia of 26% and raised ESR (48 mm at the end of 1 hour).

Ultrasound examination of the abdomen and pelvis revealed multiple, thin walled cystic lesions varying in size (from 1 to 10 cm), in the liver and spleen (fig 1a & b)and in the lesser sac anterior to body of the pancreas (fig.2). The omentum and the pouch of Douglas were studded with similar cystic lesions. These cysts showed presence of internal echoes, few of them had daughter cysts (fig3 ) in them - some with multiple septations (fig4) and floating membranes (fig 4). Plain and contrast enhanced CT scan of the abdomen and pelvis revealed multiple hydatid cysts in varying stage of development involving liver and spleen(fig5). Diffuse involvement of the peritoneum was noted(fig.6) .

Fig.1a	Fig.1b
Fig.2	Fig.3
Fig.4	Fig.5
Fig.6

DIAGNOSIS:

Based on the typical imaging findings, a diagnosis of disseminated peritoneal hydatid disease secondary to hepatic involvement was made. Serological work up was positive for E. granulosis IgG by IHA method (> 1: 320).

TREATMENT:

The patient was managed conservatively with albendazole (400 mg OD for 3 cycles of 21 days each with interval of 21 days after each cycle) and Praziquantel (1 gm od for 3 cycles of 21 days each with interval of 21 days after each cycle).

On follow up, the patient was clinically asymptomatic with marked decrease in size of the right hypochondriac lump. Follow up USG and CT was done which demonstrated significant decrease in cyst number and size in the liver , spleen and peritoneum (fig 7&8).The wall of cysts were poorly defined compared to the pre treatment scans , suggestive of response to therapy.

Fig.7	Fig.8

DISCUSSION:

Hydatid disease is a parasitic infection caused by the cestode Echinococcus granulosus. It is endemic in many parts of the world, including India. Most frequently it affects the liver and lung. Involvement of the peritoneal cavity is uncommon, accounting for 13% of abdominal echinococcosis. Hydatid disease is a zoonosis caused by larval stage of the echinococcus tapeworm. The life cycle of E. granulosus involves the dog or another carnivore as definitive hosts and sheep and other ruminants as intermediate hosts. The adult worm lives in the intestine of the definitive host and the eggs are expelled in the feces. The intermediate host ingests the ovum while grazing on contaminated ground. The ovum loses its chitinous layer as it is digested in the duodenum. The released hexacanth or oncosphere passes through the intestinal wall into the portal circulation to form a cysts in the liver. The cycle is completed when an infected intermediate host dies and its viscera is consumed by the definitive host . Man is an incidental intermediate host and acts as a dead end in the cycle.

Liver and lung are the organs most frequently affected. 'Saidis ' rule of thumb states - liver (75%) , lung (15%) and rest of body (10 %). However, no organ in body is immune to affection.

Peritoneal hydatidosis is almost always secondary to hepatic disease, although some unusual cases of primary peritoneal hydatidosis have been described . The overall frequency of peritoneal disease in cases of abdominal echinococcus is approximately 13% . Peritoneal involvement is usually undetected unless cysts are large enough to cause symptoms. Most of the cases of peritoneal hydatid disease are secondary to previous surgery for liver hydatidosis; however, spontaneous microrupture of a hepatic cyst into peritoneum have also reported . Peritoneal hydatid disease may grow and occupy the entire peritoneal cavity, simulating a multilobulated mass .This pathological condition is known as encysted peritoneal hydatidosis.

Diagnosis of hydatid disease is usually radiological and aided by serological testing. .Ultrasonogarphy (USG) is the first line of screening for abdominal hydatidosis. USG is particularly useful for detection of cystic membrane, septa, and to look for hydatid sand. CT scan best demonstrates cyst wall calcification and cyst infection. CT and USG demonstrate rupture in most cases that involve wide communication. Wider field of view and better delineation of extent of disease as well as cyst wall make CT scan imaging modality of choice in peritoneal seedling. On USG, a typical hydatid cyst appears as a well defined cystic lesion with wall formed by two echogenic line separated by a hypoechoic layer representing peri , ecto and endocyst. Simple cyst do not show any internal structure however in due course echogenic material (hydatid sand), daughter cyst and detachment of the ectocyst from pericyst can be seen (split wall or floating membrane).

CT is indicated where USG fails due to obesity or intestinal gas or disease complications. CT should also be done wherever the extent of the disease cannot be defined by USG. On CT, cyst fluid usually demonstrates water attenuation of 3-30 HU. Calcification and septa are easily demonstrated on CT. It is a useful modality to assess a patient on medical therapy as it clearly shows changes in size, number and density of lesion as seen in this patient.

In diffuse peritoneal hydatid disease, medical management is preferred. In a study by Taylor et al the combination therapy with albendazole and praziquantel was found more effective then either agent alone. After medical therapy, follow up is advisable with USG or CT scan . After medical treatment, hydatid cysts shows gradual reduction in cyst size and number .The cyst becomes poorly defined and denser. Daughter cysts may disappear or may rupture and the laminated membrane may separate from the pericyst and collapse. Thickening and calcification of the cyst wall can be taken as therapeutic response if it was absent before treatment. Cyst disappearance should be regarded as the criteria with most promising prognostic value.