Department of Pathology, University of Oklahoma Health Sciences Center
An 8 year-old boy with new onset generalized seizure.
Erin O'Leary, M.D.1, Kar-Ming Fung, M.D. Ph.D.2, Jiang Qian, M.D., Ph.D.1, Last Updated September 30,2006
1 Department of Pathology, Albany Medical College, Albany, NY and 2 Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK.
Clinical information:
The patient was an 8 year-old Caucasian boy with an unremarkable past medical history who presented to the emergency department with new-onset generalized seizures. The patient's mother reported a "fever" that occurred about one week prior to presentation and the fever lasted for about four days. The fever was not associated with upper respiratory or other constitutional symptoms. He had dental work 5 months prior to presentation, and had visited Florida two months prior, swimming in multiple pools and in the sea. Physical examination, including neurological exam, and blood/urine laboratory data were unremarkable. No cerebrospinal fluid was obtained. An MRI with gadolinium revealed a small enhancing mass in the left frontal lobe as illustrated below.
After a blood culture was obtained, the patient was started on triple antibiotics and brought to the operating room for a left frontal craniotomy with biopsy. A frozen section and touch preparation revealed acute inflammation with probable microabscess formation. Gram stain on tissue sent for aerobic, anaerobic, fungal, acid-fast bacilli, and amoebic cultures revealed no organisms. Representative images of the permanent sections are presented as follows:
Click thumbnails
to see pictures.
Neuroimaging of the case:
A small, intensely enhancing nodule is present in the left frontal lobe (arrow in MRI). The nodule is well demarcated. It does not appear to have produced excessive edema around and and there is no mass effects.
Pathology of the case:
On the permanent sections, it is obvious that a parasite is presen tand is surrounded by marked inflammatory response (Panel A). The surrounding inflammatory response is composed of lymphocytes, plasma cells, and multinucleated giant cells, with background reactive astrocytes. Reactive fibroblasts and proliferating capillaries compose the adjacent granulation tissue response (Panel B and C). The identifiable microscopic morphology of the parasite includes protoscolex with associated suckers and hooklets (Panel D). The hooklets located at the mouth part are refractile (Panel E). The larval bladder is identified with its single layer of tegumental cells and loose central stroma. The outer tegument has well-preserved surface microvilli (Panel F and G).
| DIAGNOSIS: Cerebral cysticersosis (neurocysticercosis). |
Discussion:
General Information:
Cerebral cysticersosis or neurocysticercosis is an infection by Cysticercus cellulosae, the larval metacestode of Taenia solium, also known as ork tapeworm [Click here to see the life cycle and more images of T. soliuim]. Cysticercosis was described as early as the 16th century, and continues to be a globally common cause of seizures in over 2.5 million infected people. Africa, Asia, Central America, Eastern Europe, Mexico, Portugal, and Spain are the most endemic areas, with infections more common in locales where poor sanitation prevails.
T. solium eggs from adult tapeworms contaminate the food sources of pig and cattle through fecal shedding. The bovine or porcine intermediate hosts ingest eggs that hatch in the small intestine, release oncospheres that infiltrate the mucosa, enter lymphovascular channels, and metastasize to other tissues and organ systems. The normal life cycle is completed when the definitive human host ingests encysted oncospheres in undercooked meats. An adult tapeworm develops in the human small intestine by mucosal attachment and eversion of the scolex, ultimately contributing to the transmission of more eggs through fecal shedding.
Cysticercosis is a unique syndrome caused when, instead, humans are utilized as the intermediate host by T. solium. In essence, it is caused by invasive C. cellulosae and C. racemose, the larval metacedtode of T. solium. Humans directly ingest eggs from unwashed hands, contaminated water or food. These eggs, through the development of oncospheres, lymphatically travel to the brain, eye, skin and subcutaneous tissues of the intermediate human host. Another pathogenetic pathway in the development of cysticercosis involves autoinfection by the reflux of mature T. solium tapeworm gravid proglottids into the stomach or duodenum through reverse peristalsis. The incubation period can vary from days to a full decade, with an average of 7-9 weeks.
The clinical symptoms of cysticercosis depend upon the ultimate location, quantity, and size of the metastasized oncospheres. Specifically, cerebral cysticercosis can manifest with motor and/or sensory disturbances (including hemiparesis), hydrocephalus, meningitis, or seizures, as seen in the current case. Optic nerve involvement can introduce visual disturbances to the presentation. The spinal cord is rarely involved. Physical and radiological examinations can reveal mass lesions, papilledema, reduced visual acuity, and organisms within the vitreous humor.
The preferred treatment for neurocysticersosis is albendazole, although surgical resection may be preferable in certain cases. Simultaneous steroid therapy can reduce the complications associated with cytokine-induced cerebral edema. Pre-emptive prevention of infection would include educational measures to ensure proper meat cooking and disposal of human fecal matter.
Pathology:
Grossly, the mature larva, or protoscolex, is a single organism within a milky
cyst, approximately 1 cm in maximum diameter. The protoscolex forms a white
opacity at the center of the ovoid cyst. On hematoxylin and eosin-stained
slides, the protoscolex can be identified by its four 300 um circular suckers
and 22-36 small and large hooklets arranged in a double row at the rostellum, or
tubular mouthpart. The hooklets measure between 100-130
mm,
are birefringent, and may have acid-fast positivity. The outer layer, or
tegument of the invaginating neck region measures 10-20 um in thickness. This
layer extends through a layer of smooth muscle and tegumental cells into loose,
fluid-filled parenchyma, containing calcareous corpuscles, measuring 10-20 um.
The larval bladder is identified by a thin (5 um), outer tegumental layer that
is architecturally arranged into 10-25 um-wide projections and covered by
microtriches (i.e.,microvilli).
Reference:
Neafie R, Marty A, & Johnson, L. Taeniasis and Cysticercosis in Pathology of Infectious Diseases (Ed. Meyers, WM), Volume 1: Helminthiasis, pp:117-136, AFIP, 2000.
Cases of the Month Evaluation Coordinator: KarMing-Fung@ouhsc.edu