Neuroradiology
Hydatid Cyst of the Skull: Report of Four
Cases 1
G. A. Teymoorian, M.D., and F. Bagheri, M.D. Four new cases of cranial echinococcosis are presented and the literature is reviewed. Young males are most commonly affected. Early cases present as an expansile osteolytic lesion in the diploe. The more advanced forms manifest as multilocular or unilocular destructive lesions with adjacent soft-tissue masses. Two patients with unilocular hydatid cysts recovered completely after surgery. One youth with the multilocular form died four months after operation. The other patient is well two years after surgery. The location, anatomical forms of the lesion, and the importance of early diagnosis are stressed. INDEX TERMS:
Skull, cysts. Skull, echinococcosis
Radiology 118:97-100, January 1976
• six months. No neurological abnormalities were noted on physical examination. Casoni's test was negative. A differential blood smear revealed eosinophilia. Plain films of the skull demonstrated severe expansion of the diploe of the left parietal bone, especially inward, but no destruction of the tables was seen. Several bony lamina were found on the lesion. Because of the duration of the disease and the radiological appearance, the first diagnosis was hydatid cyst of the skull. At operation, the internal table and dura mater were pushed inward; after separation of the dura, the lesion was completely removed. Recovery was uneventful.
of the skull is very rare, even in endemic areas (2, 8). The earliest reported case of cranial hydatidosis was seen by Guesnard on 1836 and the first investigation of hydatid cyst of the skull was done by Lombard and colleagues in 1871 [quoted by Arana Iniguez (2)]. By injecting scoleces into the carotid artery of rabbits, Deve showed that the spongiosa was the first part of the skull to be involved and described the pathology of Echinococcus involving the calvarium (4). Less than 100 cases of cranial hydatidosis have been reported in the medical literature, and of these only 38 have been fully investigated (2). The purpose of this paper is to report 4 new cases of cranial hydatidosis with discussion of their radiological manifestations and review of the literature. CHINOCOCCOSIS
E
CASE III. (Fig. 3). A 26-year-old laborer came to the hospital because of headaches and prominence of the occipital bone. The bulge was slightly tender and, on palpation, was found to be lobulated with an irregular consistency. The patient had first noticed the swelling about 2 %years ago. Five months before admission, headaches and intermittent vomiting had developed. Papilledema was noted on admission. The gait was unsteady but not ataxic. Casoni and Weinberg's reactions were positive. Plain films of the skull demonstrated an extensive osteolytic lesion on the occipital bone with a multicystic appearance at its periphery. Both internal and external tables were destroyed and multiple bony sequestra were also noted. The sella turcica was normal and the calcified pineal body was in its normal position. Casoni's reaction was negative but the blood smear revealed eosinophilia. Because of the radiological appearance and duration of the disease, a diagnosis of hydatid cyst of the skull was made. At operation, the tables were found to be irregularly destroyed and numerous cystic lesions were observed. The dura was thin and pushed to the bottom of the cavity which was filled with hundreds of cystic and bony necrotic particles which were removed. Follow-up over the next two years showed no evidence of recurrence.
CASE REPORTS CASE I. (Fig. I). A 9-year-old boy was admitted because of a bulge in the right parietal region, first noticed two years previously. Since that time, the lesion had slowly increased in size. On physical examination, a large, painless prominence was noted over the right parietal bone. No neurological deficits were found. Blood differential showed slight eosinophilia. The Casoni test was positive. Radiological examination of the skull revealed an extensive osteolysis of the parietal bone on the right side with a soft-tissue mass. Two curvilinear lines were seen on the inner surface of the lesion which were due to inward displacement of the internal table and dura mater. A diagnosis of cranial hydatidosis was made. At operation, a large hydatid cyst of the skull with a diverticular attachment to the inner table was revealed. The internal table was thin and pushed inward with dura mater. There was no evidence of intracranial involvement. The cystic lesion was removed with the internal table in one piece and the operation was tolerated without any complications.
CASE IV. (Fig. 4). A 12-year-old boy was brought in because of prominence of the right side of the calvarium. There was a soft-tissue swelling with no obvious neurological abnormalities. On palpation, it was painless but the consistency varied. The patient had noticed the bulge four years before admission. The lesion had gradually increased in size. Casoni's test was negative. Radiological examination of the skull revealed a large osteolytic multilocular lesion on the right parietal bone. Displacement and erosion of the tables were seen. Obvious numerous cystic lesions with multiple bony sequestra were also evident. The diagnosis was hydatid cyst of the skull but the
CASE II. (Fig. 2). A 32-year-old man was admitted with a bulging left parietal bone. On examination, a hard, bony prominance with a smooth surface was palpated. The patient had noticed this slowly growing bulge for three years, and had been suffering headaches for 1
From the Department of Radiology, Pahlavi Medical School, Tehran, Iran. Accepted for publication in August 1975.
97
shan
98
G. A.
TEYMOORIAN AND
F.
BAGHERI
January 1976
Fig. 2. CASE II. (A and B). A 32-year-old man with echinococcosis of the calvarium. Note the osteolytic expansile lesion involving the left parietal bone with no destruction of the tables (unilocular form).
was seen on the right parietal region with discharge of infected cystic material. Plain films of the skull showed that the bony lesions had advanced, causing spontaneous air encephalogram. The multilocular lesion of the right parietal bone had grown and the number of cystic areas had also increased. At operation, hydatidosis of the skull was confirmed. There was involvment of the dura and arachnoid membranes, with numerous tiny cystic lesions. After surgery, a fistula with purulent meningitis developed and the patient died four months later.
--
patient refused surgery. After nine months, he returned for treatment because of headaches and vomiting. On examination, a fistula
Fig. 1. CASE I, A through C. A 9-year-old boy with the univesicular form of cranial hydatidosis. Extensive osteolysis of the right parietal bone with adjacent extra- and intracranial (extradural) soft-tissue mass is present. Two curvilinear lines are seen on the inner surface of the lesion which were due to inward displacement of the internal table and dura mater, proved at surgery.
HYDATID CYST OF THE SKULL
Vol. 118
99
Neuroradiology
Fig. 3; CASE III. A 26-year-old man with multilocular cranial hydatidosis. Multilocular bony destruction with adjacent extradural soft-tissue mass is present. Both tables are destroyed.
DISCUSSION
Cranial hydatidosis is very rare even in endemic areas. Only 1-2 % of hydatid cysts are localized in the skeleton and.of these, only 3-4 % are in the skull (8, 9). To our knowledge, only 38 cases of cranial hydatidosis with full investigation have been reported in the literature (2) but if one includes the reported cases of intracranial and skull involvement, the incidence will be higher. When the Echinococcus granulosus lodges in the diploe, it may grow in two ways: There may be buds vegetating from the mother vesicle which produce a multiloculated cavity with diverticular extensions, or sometimes exogenous vesicles develop outside the original vesicle and myriads of new vesicles invade the spongiosa, causing bone destruction by infiltration (1, 2, 5).
In the skull, the tables are thin with low resistance and the lesion can easily break through, producing an extra- or intracranial soft-tissue hydatid mass without losing its univesicular form. In this form, a large vesicle is seen which is attached to the internal table by a pedicle and on removal may be solitary or other intraossecus vesicles may be found beneath it. This is less common than the multilocu1ar state. Usually, no bony reaction is seen around the lesion. In its unilocular form, the whole lesion may undergo calcification which probably indicates the death of the parasite (5, 8). Young males are most commonly affected. Prominence of the bone is usually the first symptom the patient will notice. All of our patients came in because of skull deformity. If the lesion extends intracranially, signs of cranial nerve involvment or intracranial hypertension may be present (2). ROENTGEN FINDINGS
In the early stages, an area of multiloculated or uniloculated bone destruction forms in the skull. The diploe is expanded and the tables are intact. No adjacent soft-
Fig. 4. CASE IV. A and B. A 12-year-old boy with a multilocular hydatidosis of the skull. An osteolytic expansile multilocular lesion of the right parietal bone is seen. Numerous sequestra are present on the lesion. Destruction of both tables is apparent. C. The same patient nine months later. A spontaneous encephalogram is obvious and the cystic lesions have enlarged.
100
G. A.
TEYMOORIAN AND
tissue mass or density is present. Usually, the calvarium is involved. In 3 of our 4 patients, the lesion was on the parietal bone. The lesion grows slowly and silently, and may remain unrecognized for many years. In the multilocular form, the areas of destruction are classically compared to a bunch of grapes. In this stage, the appearance is not pathognomonic and can be confused with fibrous dysplasia, solitary plasmocytoma, cavernous hemangioma, and epidermoid and aneurysmal bone cyst. Cranial hydatidosis, like other types of osteohydatidosis, is never self limiting and grows in all directions. Expansion of the diploe gradually increases and the tables will erode. The lesion may later break through the tables and produce a soft-tissue mass. This multilocular or unilocular destructive lesion of the skull with soft-tissue mass should be differentiated from round cell tumors, including plasmocytoma, osteolytic metastasis, and other similar conditions associated with soft-tissue masses (2, 6-9). In the unilocular form, two parallel and dense lines are usually observed on the inner side of the lesion which consist of a thin internal table and the dura mater. Sometimes, such dense iines may be seen around the lesion. In this form, complete calcification of the lesion may occur. When the hydatid cyst is located at the base of the skull, there may be bony sclerosis without an obvious multilocular or unilocular appearance. Prognosis of the unilocular form of cranial hydatidosis is more satisfactory, even at the base of the skull (2). In our series, 2 patients with unilocular hydatid cyst achieved complete recovery after surgery; 2 others had the multilocular form of the disease, one of whom died four months after operation (CASE IV); the other had no evidence of disease two years after surgery.
F.
BAGHERI
January 1976
We believe radiologists have an important role in the diagnosis of hydatid cysts of the skull. Whenever a radiologist practicing in an endemic area encounters an osteolytic expansile cranial lesion (multilocular or unilocular) he should consider the possibility of cranial hydatidosis. Life-saving surgery will then not be delayed until severe complications make the diagnosis obvious and the treatment difficult. Radiology Department Pahlavi Medical School Bayat Street Elizabeth II Boulevard Tehran 14, Iran
REFERENCES 1. Arana liiiguez R, Lopez-Fernandez JR: Parasitosis of the nervous system, with special reference to echinococcosis. Clin Neurosurg 14:123-144, 1966 2. Arana Iniguez R, Perillo W, Pereda A, et al: Echinococcose des os du crane. Neurochirurgurie 19:347-372, Jul-Aug 1973 3. Bonakdarpour A: Echinococcus disease: report of 112 cases from Iran and a review of 611 cases from the United States. Am J Roentgenol 99:660-667, Mar 1967 4. Deve FL: Echinococcose osseuse, Monteverde, ed. Montevideo, Uruguay, 1948 5. Delahaye RP, Laurent H, Massoubre A: Les aspects radlologiques de I'hydatidose osseuse (a propos de 4 observations personelles). J Radiol Electr 48:269-276, May 1967 6. King IT, Couch RSC: The diagnosis of cerebral hydatid disease. Clin RadioI12:190-193, Jul1961 7. Lagrot F, Pheline C, Azoulay C: A propos de 8 cas d'hydatidose cerebrale. Pediatrie 15:293-297, 1960 8. Samiy E, Zadeh FA: Cranial and intracranial hydatidosis, with special reference to roentgen ray diagnosis. J Neurosurg 22: 425-433, May 1965 9. Wertheimer P, Levy A, Mounier-Kuhn A, et al: Hydatidose de la voDte crarnenne. J Radiol Electrol 40:722-724, Nov 1959
Hydatid Cyst of the Skull: Report of Four
Cases 1
G. A. Teymoorian, M.D., and F. Bagheri, M.D. Four new cases of cranial echinococcosis are presented and the literature is reviewed. Young males are most commonly affected. Early cases present as an expansile osteolytic lesion in the diploe. The more advanced forms manifest as multilocular or unilocular destructive lesions with adjacent soft-tissue masses. Two patients with unilocular hydatid cysts recovered completely after surgery. One youth with the multilocular form died four months after operation. The other patient is well two years after surgery. The location, anatomical forms of the lesion, and the importance of early diagnosis are stressed. INDEX TERMS:
Skull, cysts. Skull, echinococcosis
Radiology 118:97-100, January 1976
• six months. No neurological abnormalities were noted on physical examination. Casoni's test was negative. A differential blood smear revealed eosinophilia. Plain films of the skull demonstrated severe expansion of the diploe of the left parietal bone, especially inward, but no destruction of the tables was seen. Several bony lamina were found on the lesion. Because of the duration of the disease and the radiological appearance, the first diagnosis was hydatid cyst of the skull. At operation, the internal table and dura mater were pushed inward; after separation of the dura, the lesion was completely removed. Recovery was uneventful.
of the skull is very rare, even in endemic areas (2, 8). The earliest reported case of cranial hydatidosis was seen by Guesnard on 1836 and the first investigation of hydatid cyst of the skull was done by Lombard and colleagues in 1871 [quoted by Arana Iniguez (2)]. By injecting scoleces into the carotid artery of rabbits, Deve showed that the spongiosa was the first part of the skull to be involved and described the pathology of Echinococcus involving the calvarium (4). Less than 100 cases of cranial hydatidosis have been reported in the medical literature, and of these only 38 have been fully investigated (2). The purpose of this paper is to report 4 new cases of cranial hydatidosis with discussion of their radiological manifestations and review of the literature. CHINOCOCCOSIS
E
CASE III. (Fig. 3). A 26-year-old laborer came to the hospital because of headaches and prominence of the occipital bone. The bulge was slightly tender and, on palpation, was found to be lobulated with an irregular consistency. The patient had first noticed the swelling about 2 %years ago. Five months before admission, headaches and intermittent vomiting had developed. Papilledema was noted on admission. The gait was unsteady but not ataxic. Casoni and Weinberg's reactions were positive. Plain films of the skull demonstrated an extensive osteolytic lesion on the occipital bone with a multicystic appearance at its periphery. Both internal and external tables were destroyed and multiple bony sequestra were also noted. The sella turcica was normal and the calcified pineal body was in its normal position. Casoni's reaction was negative but the blood smear revealed eosinophilia. Because of the radiological appearance and duration of the disease, a diagnosis of hydatid cyst of the skull was made. At operation, the tables were found to be irregularly destroyed and numerous cystic lesions were observed. The dura was thin and pushed to the bottom of the cavity which was filled with hundreds of cystic and bony necrotic particles which were removed. Follow-up over the next two years showed no evidence of recurrence.
CASE REPORTS CASE I. (Fig. I). A 9-year-old boy was admitted because of a bulge in the right parietal region, first noticed two years previously. Since that time, the lesion had slowly increased in size. On physical examination, a large, painless prominence was noted over the right parietal bone. No neurological deficits were found. Blood differential showed slight eosinophilia. The Casoni test was positive. Radiological examination of the skull revealed an extensive osteolysis of the parietal bone on the right side with a soft-tissue mass. Two curvilinear lines were seen on the inner surface of the lesion which were due to inward displacement of the internal table and dura mater. A diagnosis of cranial hydatidosis was made. At operation, a large hydatid cyst of the skull with a diverticular attachment to the inner table was revealed. The internal table was thin and pushed inward with dura mater. There was no evidence of intracranial involvement. The cystic lesion was removed with the internal table in one piece and the operation was tolerated without any complications.
CASE IV. (Fig. 4). A 12-year-old boy was brought in because of prominence of the right side of the calvarium. There was a soft-tissue swelling with no obvious neurological abnormalities. On palpation, it was painless but the consistency varied. The patient had noticed the bulge four years before admission. The lesion had gradually increased in size. Casoni's test was negative. Radiological examination of the skull revealed a large osteolytic multilocular lesion on the right parietal bone. Displacement and erosion of the tables were seen. Obvious numerous cystic lesions with multiple bony sequestra were also evident. The diagnosis was hydatid cyst of the skull but the
CASE II. (Fig. 2). A 32-year-old man was admitted with a bulging left parietal bone. On examination, a hard, bony prominance with a smooth surface was palpated. The patient had noticed this slowly growing bulge for three years, and had been suffering headaches for 1
From the Department of Radiology, Pahlavi Medical School, Tehran, Iran. Accepted for publication in August 1975.
97
shan
98
G. A.
TEYMOORIAN AND
F.
BAGHERI
January 1976
Fig. 2. CASE II. (A and B). A 32-year-old man with echinococcosis of the calvarium. Note the osteolytic expansile lesion involving the left parietal bone with no destruction of the tables (unilocular form).
was seen on the right parietal region with discharge of infected cystic material. Plain films of the skull showed that the bony lesions had advanced, causing spontaneous air encephalogram. The multilocular lesion of the right parietal bone had grown and the number of cystic areas had also increased. At operation, hydatidosis of the skull was confirmed. There was involvment of the dura and arachnoid membranes, with numerous tiny cystic lesions. After surgery, a fistula with purulent meningitis developed and the patient died four months later.
--
patient refused surgery. After nine months, he returned for treatment because of headaches and vomiting. On examination, a fistula
Fig. 1. CASE I, A through C. A 9-year-old boy with the univesicular form of cranial hydatidosis. Extensive osteolysis of the right parietal bone with adjacent extra- and intracranial (extradural) soft-tissue mass is present. Two curvilinear lines are seen on the inner surface of the lesion which were due to inward displacement of the internal table and dura mater, proved at surgery.
HYDATID CYST OF THE SKULL
Vol. 118
99
Neuroradiology
Fig. 3; CASE III. A 26-year-old man with multilocular cranial hydatidosis. Multilocular bony destruction with adjacent extradural soft-tissue mass is present. Both tables are destroyed.
DISCUSSION
Cranial hydatidosis is very rare even in endemic areas. Only 1-2 % of hydatid cysts are localized in the skeleton and.of these, only 3-4 % are in the skull (8, 9). To our knowledge, only 38 cases of cranial hydatidosis with full investigation have been reported in the literature (2) but if one includes the reported cases of intracranial and skull involvement, the incidence will be higher. When the Echinococcus granulosus lodges in the diploe, it may grow in two ways: There may be buds vegetating from the mother vesicle which produce a multiloculated cavity with diverticular extensions, or sometimes exogenous vesicles develop outside the original vesicle and myriads of new vesicles invade the spongiosa, causing bone destruction by infiltration (1, 2, 5).
In the skull, the tables are thin with low resistance and the lesion can easily break through, producing an extra- or intracranial soft-tissue hydatid mass without losing its univesicular form. In this form, a large vesicle is seen which is attached to the internal table by a pedicle and on removal may be solitary or other intraossecus vesicles may be found beneath it. This is less common than the multilocu1ar state. Usually, no bony reaction is seen around the lesion. In its unilocular form, the whole lesion may undergo calcification which probably indicates the death of the parasite (5, 8). Young males are most commonly affected. Prominence of the bone is usually the first symptom the patient will notice. All of our patients came in because of skull deformity. If the lesion extends intracranially, signs of cranial nerve involvment or intracranial hypertension may be present (2). ROENTGEN FINDINGS
In the early stages, an area of multiloculated or uniloculated bone destruction forms in the skull. The diploe is expanded and the tables are intact. No adjacent soft-
Fig. 4. CASE IV. A and B. A 12-year-old boy with a multilocular hydatidosis of the skull. An osteolytic expansile multilocular lesion of the right parietal bone is seen. Numerous sequestra are present on the lesion. Destruction of both tables is apparent. C. The same patient nine months later. A spontaneous encephalogram is obvious and the cystic lesions have enlarged.
100
G. A.
TEYMOORIAN AND
tissue mass or density is present. Usually, the calvarium is involved. In 3 of our 4 patients, the lesion was on the parietal bone. The lesion grows slowly and silently, and may remain unrecognized for many years. In the multilocular form, the areas of destruction are classically compared to a bunch of grapes. In this stage, the appearance is not pathognomonic and can be confused with fibrous dysplasia, solitary plasmocytoma, cavernous hemangioma, and epidermoid and aneurysmal bone cyst. Cranial hydatidosis, like other types of osteohydatidosis, is never self limiting and grows in all directions. Expansion of the diploe gradually increases and the tables will erode. The lesion may later break through the tables and produce a soft-tissue mass. This multilocular or unilocular destructive lesion of the skull with soft-tissue mass should be differentiated from round cell tumors, including plasmocytoma, osteolytic metastasis, and other similar conditions associated with soft-tissue masses (2, 6-9). In the unilocular form, two parallel and dense lines are usually observed on the inner side of the lesion which consist of a thin internal table and the dura mater. Sometimes, such dense iines may be seen around the lesion. In this form, complete calcification of the lesion may occur. When the hydatid cyst is located at the base of the skull, there may be bony sclerosis without an obvious multilocular or unilocular appearance. Prognosis of the unilocular form of cranial hydatidosis is more satisfactory, even at the base of the skull (2). In our series, 2 patients with unilocular hydatid cyst achieved complete recovery after surgery; 2 others had the multilocular form of the disease, one of whom died four months after operation (CASE IV); the other had no evidence of disease two years after surgery.
F.
BAGHERI
January 1976
We believe radiologists have an important role in the diagnosis of hydatid cysts of the skull. Whenever a radiologist practicing in an endemic area encounters an osteolytic expansile cranial lesion (multilocular or unilocular) he should consider the possibility of cranial hydatidosis. Life-saving surgery will then not be delayed until severe complications make the diagnosis obvious and the treatment difficult. Radiology Department Pahlavi Medical School Bayat Street Elizabeth II Boulevard Tehran 14, Iran
REFERENCES 1. Arana liiiguez R, Lopez-Fernandez JR: Parasitosis of the nervous system, with special reference to echinococcosis. Clin Neurosurg 14:123-144, 1966 2. Arana Iniguez R, Perillo W, Pereda A, et al: Echinococcose des os du crane. Neurochirurgurie 19:347-372, Jul-Aug 1973 3. Bonakdarpour A: Echinococcus disease: report of 112 cases from Iran and a review of 611 cases from the United States. Am J Roentgenol 99:660-667, Mar 1967 4. Deve FL: Echinococcose osseuse, Monteverde, ed. Montevideo, Uruguay, 1948 5. Delahaye RP, Laurent H, Massoubre A: Les aspects radlologiques de I'hydatidose osseuse (a propos de 4 observations personelles). J Radiol Electr 48:269-276, May 1967 6. King IT, Couch RSC: The diagnosis of cerebral hydatid disease. Clin RadioI12:190-193, Jul1961 7. Lagrot F, Pheline C, Azoulay C: A propos de 8 cas d'hydatidose cerebrale. Pediatrie 15:293-297, 1960 8. Samiy E, Zadeh FA: Cranial and intracranial hydatidosis, with special reference to roentgen ray diagnosis. J Neurosurg 22: 425-433, May 1965 9. Wertheimer P, Levy A, Mounier-Kuhn A, et al: Hydatidose de la voDte crarnenne. J Radiol Electrol 40:722-724, Nov 1959
