History
This is an eighteen-month old child born of Mexican extraction resident in Texas, USA . His prenatal and natal histories are unremarkable.

Figure 1: Neurocysticercosis in an 18-month child. a. Sagittal T1 without gadolinium; b. Axial T1 with gadolinium; c. Axial T2; d. Coronal FLAIR

Radiologic diagnosis: Neurocysticercosis.

Radiologic differential diagnosis
1. Pyogenic abscesses.
2. Tuberculomas.
3. Metastases.
4. Tuberous sclerosis.
5. Toxoplasmosis.

Discussion
Neurocysticercosis results when encysted larval forms of Taenia solium (pork tapeworm) invade the central nervous system (2). It is the most common parasitic disorder of the CNS (5) occurring in 4% of autopsy series from endemic countries of the world (in Latin America, Asia, Africa and some European countries).

Taenia solium is one of the eight cestode species that infect man (see Table 1). Humans are the definitive host for the parasite (we harbor the adult worm) while omnivorous or herbivorous vertebrates (like pig) host its larval form (intermediate host). Although the adult forms of the cestodes that we host rarely cause us harm, humans suffer variable degrees of illnesses when they host the larval forms; in the former case the parasites often reside harmlessly in the bowels, while in the latter they invade the tissues. For example, in its normal life cycle, humans harbor the pork tapeworm and shed its eggs (either individually or in proglottides impregnated with eggs) in our feces. The pig, an omnivore and its natural intermediate host, consumes the eggs of the parasite, which hatch into larval forms in its alimentary tract and invade its tissues. Consumption of undercooked meat from infected pork by us completes the cycle, freeing the encysted larvae when they encounter our gastric acid and bile salts. In contrast, we act as the intermediate host of the parasite when we ingest the tapeworm eggs by eating food infected with them (the infant’s mother in this case may have infected her child this way). Their larvae invade the bowel walls and invade our tissues as far afield as the brain, eyes, muscles, heart and other places wreaking havoc in their wake (7). In the CNS, the cysticerci (the larvae) may lodge in the brain parenchyma, the spinal cord, the subarachnoid space or the ventricles, lying dormant for years or causing various categories of clinical disease (see Table 2) (3).

However, 2 to 10 years after CNS invasion, the dormant cysts may die, lose osmoregulation, absorb fluid and disintegrate, releasing antigens that set up variable degrees of inflammation. The clinical conundrum that results from CNS larval invasion depends upon the size of the invasion, and the location and degree of the inflammation. You can make a sure diagnosis of neurocysticercosis by analyzing infected tissue microscopically. But you can make a presumptive diagnosis of the disease if your patient is from or resides in an endemic area (as in this case) and, if laboratory analysis of their CSF specimen including an immunoblot test, and their CNS imaging results are positive for markers of the disease (4,5) (see Table 3). 

For cysts that cause symptoms outside the CNS, surgical resection achieves cure. The treatment of symptomatic neurocysticercosis, which carries a 50% mortality rate, is more problematic. Two drugs, albendazole and praziquantel control symptoms and cause regression in the size and number of cysts in patients with viable (non-enhancing) cysts in their brain parenchyma. However, they provide limited improvement in patients with arachnoiditis and none in patients with intraventricular cysts. These latter patients should be treated with surgery or palliated with ventricular shunting, anticonvulsants, and anti-inflammatory drugs. According to our case’s physician, he did not receive anti-parasitic medication because the imaging features suggested that the parasites were dying (vasogenic edema and ring enhancement) (6).

Two cautionary injunctions about treatment, though: first, 20% of patients with parenchymal cysticercosis worsen symptomatically following the institution of drug treatment as the parasites die and release their antigens. Concomitant administration of anti-inflammatory drugs subdues this phenomenon. Second, because anti-inflammatory agents alter the CNS pharmakokinetics of the anti-parasitic agents, their routine use is discouraged.

You should rescan your patients 3 months after therapy to judge their response to treatment; prescribe an alternate drug to the one used ab initio if there is no response.

For patients with ocular cysticercosis (remember, 20%), you are better off holding drug treatment until resection of their lesions because they do not respond well to medication.

Bibliography
1. Shandera WX, White AC Jr, Chen JC, Diaz P, Armstrong R. Neurocysticercosis in Houston, Texas. A report of 112 cases. Medicine (Baltimore). 1994 Jan;73(1):37-52.
2. Domenici R, Matteucci L, Meossi C, Stefani G, Frugoli G. Neurocysticercosis: a rare cause of convulsive crises Pediatr Med Chir. 1995 Nov-Dec;17(6):577-81. Italian.
3. Caparros-Lefebvre D, Lannuzel A, Alexis C, Strobel M, Janky E Cerebral cysticercosis: why it should be treated. Presse Med. 1997 Nov 1;26(33):1574-7. French.  
4. Ruiz-Garcia M, Gonzalez-Astiazaran A, Rueda-Franco F. Neurocysticercosis in children. Clinical experience in 122 patients. Childs Nerv Syst. 1997 Nov-Dec;13(11-12):608-12.
5. Grill J, Pillet P, Rakotomalala W, Andriantsimahavandy A, Esterre P, Boisier P, Guyon P. Neurocysticercosis: pediatric aspects Arch Pediatr. 1996 Apr;3(4):360-8. Review. French.
6. Riley T, White AC Jr. Management of neurocysticercosis. CNS Drugs. 2003;17(8):577-91. Review.
7. Rahalkar MD, Shetty DD, Kelkar AB, Kelkar AA, Kinare AS, Ambardekar ST The many faces of cysticercosis. Clin Radiol. 2000 Sep;55(9):668-74.

Acknowledgement
The author acknowledges the untiring work of Obidike Nwakudu, MD in the preparation of this article, while he was a resident in Family Medicine at Mount Sinai hospital, Chicago, IIinois.

History
The patient is an elderly woman seen in a clinic because of persistent mid-back pain. She did not return to her primary care physician after this study; little of her history is available. These are the only imaging studies available in her records.  

Radiologic findings
The radiographs are frontal and lateral views of her thoracic spine.  They show:  
1. Diffuse osteopenia.
2. Levoscoliosis of the mid and lower thoracic spine.
3. Compression fractures of the eighth and ninth thoracic vertebrae.
4. Numerous round well-defined soft-tissue masses attached to the chest wall.

The key to the radiologic diagnosis of this case lies in the non-calcified cutaneous masses of varying sizes. It is easy to assume the masses are within the patient’s thorax but a closer look shows that most are well-defined, have lucent halos around them and, so, are  external to the chest wall. They are pathognomonic of von Recklinghausen’s disease (neurofibromatosis type1). The patient is osteoporotic and the vertebral compression fractures may be due to this.

Vertebral compression fractures are common in the elderly, especially in the setting of osteoporosis. They may also occur in conditions that weaken the vertebrae such as metastatic disease, infection, Scheuermann’s disease (multiple, contiguous intraosseous herniation of nucleus pulposus at the center of weakened endplates (multiple Schmorl’snodes)), sickle-cell anemia and histiocytosis X. Again, the cutaneous masses make the diagnosis easy.   Scoliosis and kyphoscoliosis of the spine may be congenital or acquired. When congenital they are due to failure of segmentation or formation of vertebral bodies; they may be mixed, showing features of both.   There are many acquired causes of scoliosis and kyphoscoliosis (see below) and painful conditions and von Recklinghausen disease are two such entities.  The upper and lower vertebrae in the patient show subtle signs of formation failure suggesting that in her the scoliosis is congenital (a component of the von Recklinghausen conundrum). Clearly, pain from the compression fractures may contribute to the abnormal spinal curvature. Thus, in the patient, congenital and acquired scoliosis may be at play.  

Radiologic differential diagnosis
For multiple cutaneous masses:
The cutaneous masses in this patient are pathognomonic for neurofibromatosis
For scoliosis:
1. Mesodermal and neuroectodermal diseases including neurofibromatosis, Marfan’s syndrome,   homocystinuria.
2. Neuromuscular diseases such as myelomeningocele, spinal muscular atrophy, Friedrich’s ataxia, poliomyelitis, cerebral palsy, and muscular dystrophy.
3. Painful scoliosis as in osteoid osteoma, osteoblastoma, intraspinal tumor, and infection.
4. Congenital scoliosis due to failure of formation, failure of segmentation, or mixed defects.
For multiple collapsed vertebrae:
1. Osteoporosis
2. Neoplastic disease
3. Scheuermann disease
4. Infection
5. Histiocytosis X
6. Sickle-cell anemia

Discussion
Neurofibromatosis type 1 (NF1) is the most common of the phakomatoses, a heterogeneous group of histiogenetic disorders characterized by the presence of central nervous system and, for the most part, cutaneous manifestations. Many also have prominent visceral and connective tissue abnormalities.

NF-1 occurs in one of 2000 to 3000 births. It is inherited by autosomal dominant transmission but has a high spontaneous mutation rate (50%) so that it may occur in offsprings of unaffected parents. The penetrance of the disease is high but its expressivity variable. The problem in the disease lies in the long arm of chromosome 17; there is neuroectodermal and mesodermal tissue dysplasia with potential for diffuse systemic involvement. Males and females are affected equally.
 
The clinical diagnosis of the disease hinges upon the demonstration of the characteristic cutaneous manifestations or two of the set of criteria shown below. The case in question has numerous cutaneous masses that are consistent with disease although we do not have a full account of the patient’s history.
 
 The NIH Consensus Development Panel developed a set of diagnostic criteria for NF-1 that includes the following:
 1. 6 or more 5mm or larger café-au-lait spots.
 2. 1 plexiform neurofibroma or two or more neurofibromas of any type.
 3.  2 or more pigmented iris hamartomas (so-called Lisch nodules).
 4.  Axillary or inguinal region freckling.
 5.  Optic nerve glioma
 6.  First-degree relative with NF-1
 7.  Presence of a characteristic bone lesion (e.g. dysplasia of the greater wing of the sphenoid, pseudoarthrosis).
 
The disease may affect many organs including the brain, spinal cord, peripheral nerves, bones, the dura, the eye and the blood vessels (see below).

NF-1 is different from NF-2 although it, too, is inherited by autosomal dominant transmission. NF-2 is less common than NF-1 (1:50,000), is due to defects in chromosome 22 and in it, cutaneous manifestations are rare. The dominant mode of presentation of NF-2 is by central nervous system lesions (approximately 100%). These include schwannomas of cranial and peripheral nerves, meningiomas in the brain and spine (often multiple), nonneoplastic intracranial calcifications (especially choroids plexus), spinal cord ependymomas and secondary changes of the spine.

 
References
1. Smirniotopoulos JG, Murphy FM: The phakomatoses, AJNR 13: 725-746, 1992.
2. Huson SM, Harper PS, Compston DA: von Recklinghausen neurofibromatosis: a clinical and population study in southeast Wales, Brain 111:1355-1381, 1988.
3. National Institute of Health  Consensus Development Conference: Neurofibromatosis Conference Statement, Arch Neurol 45: 579-588, 1988
4. Diagnostic Neuroradiology, Anne G. Osborn

History
This is a 20-year old female who visited the emergency department because of pain in the left lower quadrant of her abdomen. She had no significant past medical problems, but on examination had an excessive amount of hair on her lips, chest, and lower belly. Her pubic hair, though also excessive, was feminine in its distribution. While in the emergency department she had contrast-enhanced CT scan of her abdomen and pelvis, but had no other imaging studies. Measurements of her testosterone while on admission were normal. Later, she underwent open laparotomy and had her abdominal mass removed.

Radiologic findings

This is a single axial section through the patient’s false pelvis showing a midline, thin-walled (1mm), complex  mass. The mass measures 12cm x 13cm x 13cm and at its 10 to 12 o’clock position is a heterogeneous mass of tissue (Rokitansky protuberance, dermoid plug) comprising a high-density rectangular structure (coarse calcification, mal-formed tooth), and lobules of tissue isodense to subcutaneous fat (fat). The preponderance of the mass, however, is hypodense to enhanced muscle but slightly hyperdense to noncontrast urine (not shown); it is fatty debris. The mass is anterior to the rectum, straddles the pelvis and displaces the small bowel to the sides. The ovaries are not discernible. The appearance of the mass is pathognomonic for a mature teratoma.

Differential radiologic diagnosis
There is no differential diagnosis. The radiologic features of the lesion are pathognomonic for benign cystic teratoma of the ovary.

Gross pathologic findings
A large mass which on sectioning revealed:
1. Cheesy liquid debris.
2. A solitary tooth.
3. Thick golden-yellow congealed fatty tissue.
4. A loch of hair.
Please see below.

Final pathologic diagnosis
Mature (Benign) Cystic Teratoma.

Discussion
Teratomas (teratos, Greek for monster) are congenital tumors of derivatives of all three germ layers. They arise from pluripotent embryonal cells and occur in the ovaries, testes, mediastinum, retroperitoneum, and the sacrococcygeal region, in order of decreasing frequency. The location of the tumor in our case suggests that it is ovarian in origin; presacral or retroperitoneal origins are less likely alternatives.

Teratomas are the most common tumors of the ovary in children and adolescents although they may present at any age in life. They may be mature (cystic) or immature (solid, a.k.a embryonal) and carry a 0.25-1.5% risk of malignant degeneration, representing 1% of malignant ovarian tumors. The risk of malignant degeneration is predicted by the presence of neuroectodermal remnants, which the present case lacks.

Two-thirds (67%) of the cases present as an abdominal mass (as in this case) and 10% – 15% are bilateral. Other modes of presentation include abdominal pain (our case), ovarian torsion, nausea, vomiting and, rarely, ascites. There may be rare association with hyperprolactinemia, hemolytic anemia, hyperthyroidism (struma ovarii) or Mayer-Rokitansky-Kuster-Hauser syndrome. The latter consists of a lack of mullerian development, congenital absence of the vagina and rudimentary uterus (typically bicornuate remnants), with normal uterine tubes, ovaries, secondary female sex characteristics and normal growth.  There was mention to me by one of the patient’s physicians that she had a small uterus and was hirsute. I doubt that we can invoke Mayer-Rokitansky-Kuster-Hauser syndrome in this case because of the absence of the other features and I doubt that her alleged hirsutism has any relationship to the teratoma. She recuperated well from her surgery and went home in good condition.

References
1. Friedman AC, Pyatt RS, Hartman DS et al 1982. CT of benign cystic teratomas. AJR 138: 659-665.
2. Buy JN et al. Cystic Teratoma of the ovary: CT detection; Radiology 171: 699-701.  1989
3. Kallenberg GA et al. Ectopic hyperprolactinemia resulting from an ovarian teratoma: JAMA, 263: 2472-2474.