Primary hydatid cyst of the head and neck diagnosed with ultrasound and computed tomography: a report of two cases.

Abstract: Hydatid cysts of the head and neck are rare, even in countries where echinococcal infestation is endemic. This report presents two patients with hydatid cyst, diagnosed using ultrasonography and computed tomography, in whom the cysts were located between the right cervical paravertebral muscles and below the superficial muscles of the right temporal region.

Key Words: computed tomography, head and neck, hydatid cyst, ultrasonography

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Hydatid disease is an important infestation caused by the parasite Echinococcus granulosis and is still common in the countries of the temperate zones, including the Mediterranean countries, the Middle East, South America, New Zealand, Australia, and Southeast Asia. (1) The liver is the most frequently involved organ (75%), followed by the lung (15%) and the remainder of the body (10%). (2)

Imaging modalities such as ultrasonography, CT, and MRI are more sensitive than serologic tests in the diagnosis of hydatid cysts. (3)

We present two cases of hydatid cyst with an unusual location; the head and neck, and discuss the imaging modalities.

Case 1

A 33-year-old male was admitted to our hospital because of a slowly growing mass in the right side of his neck. His medical history was unremarkable. The physical examination revealed a 3 X 4 cm, painless, immobile mass in the right posterior region of the neck. The ultrasound examination showed a 3 X 4 cm, cystic mass with a detached germinative membrane. The CT scan, with intravenous contrast media, showed a 3 X 4 cm, well-defined, cystic mass with a detached germinative membrane that was located between the paravertebral muscles in the right cervical region (Fig. 1). Chest radiography and abdominal ultrasonography were normal. Serologic tests for hydatid disease were negative. Hydatid disease was confirmed histopathologically after surgical removal of the cystic mass.

Case 2

A 34-year-old female was admitted to the hospital because of a slowly growing, swollen mass in the right temporal region. On physical examination, a 2 X 3 cm, immobile, hard mass located in the right temporal region was detected. The ultrasound examination showed a 2 X 3 cm, multiseptated cystic mass with daughter cysts (Fig. 2). CT scan, with the use of intravenous contrast media, showed a 2 X 3 cm, well-defined, rounded cystic mass with a few septations (Fig. 3a). In addition, a remodeling process of the right temporal bone due to the pressure effect of the mass was detected (Fig. 3b). Serologic tests for hydatid disease were negative. Chest radiography and abdominal ultrasound were normal. Preoperative diagnosis of hydatid disease was confirmed histopathologically after surgical removal of the cystic mass. Clinical and radiologic details of both cases are summarized in Table 1.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

Discussion

Hydatid disease is a parasitic infestation caused by the tapeworm E granulosis. Although most cysts are caught in the hepatic sinusoids, which are carried out by the portal vein, making the liver the most frequently involved organ, a few ova may pass through the liver, heart, and pulmonary capillaries and reach the general circulation to lodge in such sites as the orbit, heart, thyroid gland, lung, bones, urinary bladder, and other internal organs. (4,5) Passage through the hepatic sinusoids, dissemination through the lymphatic channels of the intestine, inhalation of the infected material, and direct contamination by infected teeth are the possible routes for cases with solitary cysts in uncommon sites. (6)

Hydatid cysts located in the head and neck region are extremely rare, even in geographic areas in which echinococcal infestation is frequent. (4,7) In the presented patients, the cysts were located between the right paravertebral muscles of the neck and below the superficial muscles of the right temporal region. The clinical course depends on the site of involvement, the size, and pressure caused by the enlarged cysts. (8) A painless mass was the main complaint, with a pressure effect on the temporal bone in the second patient.

The ultrasound, CT, and MRI have recently become the most sensitive of diagnostic modalities. (7) The ultrasonographic examination shows the membranes, septations, and daughter cysts within the cystic cavity. (2) Multivesicular cysts are manifested as well-defined fluid collections in a honeycomb pattern with multiple septa representing the walls of the daughter cysts as in the second patient. The CT examination shows detachment of the laminated membrane as linear areas of increased attenuation within the cyst, known as "water lilly sign," as in the first patient. In addition, CT scanning provides a precise assessment of the relation between the cysts and osseous structures, the extension into the soft tissues, and the calcifications of the peripheral rim of the cyst. (9) The MRI detects the anatomic location of the cyst and involvement of the neural structures more precisely than the other methods but seems to be less helpful than CT for showing osteolytic changes. (10) The signal from the cysts is inhomogeneous of low intensity on [T.sub.1]-weighted and high-intensity on [T.sub.2]-weighted images.

The serologic tests including direct hemagglutination, latex agglutination, immunoelectrophoresis, skin tests, and enzyme-linked immunosorbent assay are widely used to confirm the diagnosis, although they are associated with false-negative and false-positive results. (11) Therefore, imaging modalities remain more sensitive than serodiagnosis, especially with unusual cyst locations, and a characteristic scan in the presence of negative serologic results should still suggest the diagnosis of echinococcosis. (3)

Treatment options for the uncomplicated hydatid cyst are various and include needle aspiration under ultrasound guidance, laparoscopic approach, direct surgical intervention, or medical treatment with the use of albendazole. (1,11,12)

In conclusion, hydatid disease should be considered in the differential diagnosis in patients with cystic masses in the head and neck regions. Ultrasound and CT findings are usually diagnostic for the hydatid disease.

References

1. Akhan O, Dincer A, Gokoz A, et al. Percutaneous treatment of abdominalhydatid cysts with hypertonic saline and alcohol: an experimental study insheep. Invest Radiol 1993;28:121-127.

2. Beggs I. The radiology of hydatid disease. AJR Am J Roentgenol 1985;145:639-648.

3. King CH. Cestodes In: Mandell GL, Bennett JE, Dolin R (eds) Principles and practice of infectious diseases, vol II. Churchill Livingstone, Philadelphia, 2000, pp 2956-2964.

4. Eroglu A, Atabekoglu S, Kocaoglu H. Primary hydatid cyst of the neck. Eur Arch Otorhinolaryngol 1999;256:202-204.

5. Bickers WM. Hydatid disease of the female pelvis. Am J Obstet Gynecol 1970;107:477-483.

6. Cetin, ET, Ang O, Toreci K. In: Cetin ET. Echinococcus Species: Medical Parasitology. 5th ed. Istanbul, University Press, 1995, pp 248-257.

7. Tekin M, Osma U, Yaldiz M, et al. Preauricular hydatid cyst: an unusual location for echinococcosis. Eur Arch Otorhinolaryngol 2004;261:87-89.

8. Gangopadhyay K, Abuzeid MO, Kfoury H. Hydatid cyst of the pterygopalatine-infratemporal fossa. J Laryngol Otol 1996;110:978-980.

9. Tsitouridis I, Dimitriadis AS. CT and MRI in vertebral hydatid disease. Eur Radiol 1997;7:1207-1210.

10. El Kohen A, Benjelloun A, El Quessar, A, et al. Multiple hydatid cystsof the neck, the nasopharynx and the skull base revealing cervical vertebral hydatid disease. Int J Pediatr Otorhinolaryngol 2003;67:655-662.

11. Senyuz OF, Celayir AC, Kilic N, et al. Hydatid disease of the liver in childhood. Pediatr Surg Int 1999;15:217-20.

12. Senyuz OF, Yesildag E, Celayir S. Albendazole therapy in the treatment of hydatid liver disease. Surg Today 2001;31:487-91.

Ibrahim Adaletli, MD, Remzi Yigiter, MD, Dogan Selcuk, MD, Akif Sirikci, MD, and Osman Faruk Senyuz, MD

From the Radiology Department and the Pediatric Surgery Department, Istanbul University, Cerrahpasa Medical Faculty; and the Medical Faculty, Neurology Department, Gaziantep University, Istanbul, Turkey.

Reprint requests to Ibrahim Adaletli, Istanbul University, Cerrahpasa Medical Faculty, Department of Radiology, 34300-Istanbul, Turkey. Email: [e-mail]

Accepted March 23, 2005.

RELATED ARTICLE: Key Points

* Hydatid cysts located in the head and neck region are extremely rare, even in geographical areas in which echinococcal infestation is frequent.

* In the presented patients, the cysts were located between the right paravertebral muscles of the neck and below the superficial muscles of the right temporal region.

* Ultrasound and computed tomography findings are usually diagnostic for hydatid disease.

Table. Summarized clinical and radiologic details of two cases with head
and neck hydatid cyst

Case       Age                                  Size
No.   Sex  (yr)  Symptoms       Location        (cm)  Ultrasound

1     M    33    Painless mass  Right side of   4     Cystic mass
                                  the neck              containing a
                                                        detached
                                                        membrane
2     F    34    Painless mass  Right temporal  3     Cystic mass with
                                  region                multiple
                                                        daughter cysts

Case                                    Serologic
No.   CT                           tests      Therapy

1     Well-defined cystic mass     Negative   Surgery
        with detached germinative
        membrane
2     Well-defined cystic mass     Negative   Surgery
        with a few septations

M, male; F, female.