A tuberculoma is a clinical manifestation of tuberculosis which conglomerates tubercles into a firm lump, and so can mimic cancer tumors of many types in medical imaging studies. [1] [2] They often arise within individuals in whom a primary tuberculosis infection is not well controlled. [3] When tuberculomas arise intracranially, they represent a manifestation of CNS tuberculosis. [3] Since these are evolutions of primary complex, the tuberculomas may contain caseum or calcifications.
With the passage of time, Mycobacterium tuberculosis can transform into crystals of calcium. These can affect any organ such as the brain, [4] [5] intestine, [6] [7] [8] ovaries, [9] [10] breast, [11] [12] [13] lungs, [14] [15] esophagus, [16] pancreas, [17] bones, [18] [19] and many others. Even with guideline-directed treatment they often persist for months to years. [3]
The exact mechanism of tuberculoma development has not been determined, although multiple theories have been proposed. It is possible that, following an initial tuberculosis infection resulting in bacteremia, a foci of granulomatous inflammation may coalesce into a caseous tuberculoma. [20] Pulmonary tuberculomas may arise due to repeated cycles of necrosis and re-encapsulation of foci, or, alternatively, the shrinkage and fusion of encapsulated densities. [21]
In regards to CNS tuberculoma, it is thought that mycobacterium tuberculosis is capable of penetrating the blood brain barrier after bacterial bacilli induce the release of cytokines by various immunologic cells, leading to an increase in barrier permeability. [22] Similar to pulmonary tuberculomas, small lesions eventually coalesce and undergo both necrosis and enlargement. [22]
Symptoms are based on the location of the tuberculoma. Small, scattered lesions may be asymptomatic. Intracranial tuberculomas in children are often infratentorial, occurring near the cerebellum and base of the brain. In this population, symptoms such as headache, fever, focal neurologic findings and seizures have been seen [3] in addition to papilledema with or without meningitis. [20] When the size of a brainstem tuberculoma grows to the point of narrowing the fourth ventricle, obstructing hydrocephalus and its related symptoms can arise. [20] Rupture of tuberculomas adjacent to the arachnoid can lead to arachnoiditis, [23] while rupture near the subarachnoid space or ventricular system can cause meningitis. [22]
The diagnosis of tuberculoma can be challenging, as invasive testing may be required and, occasionally, concomitant malignancy may be present. [21] In children with tuberculoma, CXR is often normal despite a positive TST/IGRA. [3]
Diagnosis of brain tuberculoma can be aided with PCR of cerebrospinal fluid, but is of less utility for quickly diagnosing and treating lesions. [22] When CSF is analyzed in patients with suspected tuberculoma, high protein concentrations and cell counts are often seen. [24]
Definitive diagnosis can be made through stereotactic, CT-guided biopsy, with excision required in rare cases. Biopsy is chosen when non-invasive testing has failed to produce a diagnosis, when patients fail to respond to a treatment regimen, in cases of drug-resistant tuberculosis, and in non-compliant patients. [22]
The appearance of a tuberculoma on imaging can vary according to the composition and age of the mass. They may appear as either non-caseating or solidly caseating lesions. [20] Initially, tuberculomas appear hypodense on computed tomography (CT) scans with significant surrounding edema. [23] [3] The "target sign" is pathognomonic for tuberculoma on CT, with a nodular ring-enhancing mass and central calcification. [24] [20] The characteristic ring-enhanced appearance is due to lack of blood supply in the central necrotic core that is visualized with injected contrast. [22] Sometimes a hypodense central area is seen instead of calcification. [25] When considering other potential intracranial masses in a differential diagnosis, such as cysticercosis, pyogenic abscess, and neoplastic lesions, tuberculoma can be identified by its larger size (>2 cm), edema, and irregular border.
Magnetic resonance imaging (MRI) is another useful imaging modality for diagnosing and characterizing of tuberculomas, especially solid caseous necrosis in which 3 zones of varying intensity are seen. [22]
Tuberculoma is commonly treated through the HRZE drug combination (Isoniazid, Rifampin, Pyrazinamide, Ethambutol) followed by maintenance therapy. [26] Per international guidelines, 9–12 months of medical management is standard. [20] While the majority of tuberculomas resolve in 12–24 months, in patients with multiple or larger lesions prolonged treatment extending beyond two years may be required. In some patients, the release of inflammatory mediators during treatment can cause a paradoxical worsening of symptoms that is treated with anti-inflammatory medications in addition to the standard anti-tuberculosis regimen. [22]
Exceptionally large tuberculomas, those exerting a mass effect on the brain, and those which fail to respond to medical management required surgical excision. In some cases, surgical excision is necessary for diagnosis as well as treatment. [3] When intracranial pressure rises in the setting of tuberculoma, removal is considered a surgical emergency. [22]
Of patients with a brain tuberculoma treated with an appropriate medication regimen, almost half recover completely. Approximately 10% of those treated fail to recover and succumb to the tuberculoma. [22] Reports issued before the advent of effective anti-tuberculosis therapy showed that, when untreated, 30-50% of tuberculomas enter and remain in a stationary course. [21]
Tuberculomas are most commonly seen in areas where tuberculosis is endemic. In these areas, tuberculomas can account for between 30%-50% of intracranial masses. [22] [3] India and parts of Asia are two areas where tuberculomas have been noted to be particularly prevalent. [20] They occur most often as solitary, infratentorial lesions in young children. [3] In contrast, lesions are most often supratentorial in adults. [3]
Pulmonary tuberculomas are among the most common benign nodules, with 5%-24% of all resected nodules being of tuberculous origin. [21] In areas of lower prevalence, such as the United States, they are most commonly seen in the setting of an acquired immunodeficiency. [23] Intracerebral tuberculomas, specifically, are more frequently observed in patients with an HIV infection. [20]
Brain abscess is an abscess within the brain tissue caused by inflammation and collection of infected material coming from local or remote infectious sources. The infection may also be introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.
A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant (cancerous) tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and secondary tumors, which most commonly have spread from tumors located outside the brain, known as brain metastasis tumors. All types of brain tumors may produce symptoms that vary depending on the size of the tumor and the part of the brain that is involved. Where symptoms exist, they may include headaches, seizures, problems with vision, vomiting and mental changes. Other symptoms may include difficulty walking, speaking, with sensations, or unconsciousness.
Tuberous sclerosis complex (TSC) is a rare multisystem autosomal dominant genetic disease that causes non-cancerous tumours to grow in the brain and on other vital organs such as the kidneys, heart, liver, eyes, lungs and skin. A combination of symptoms may include seizures, intellectual disability, developmental delay, behavioral problems, skin abnormalities, lung disease, and kidney disease.
Radiology (X-rays) is used in the diagnosis of tuberculosis. Abnormalities on chest radiographs may be suggestive of, but are never diagnostic of TB, but can be used to rule out pulmonary TB.
Miliary tuberculosis is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1–5 mm). Its name comes from a distinctive pattern seen on a chest radiograph of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds—thus the term "miliary" tuberculosis. Miliary TB may infect any number of organs, including the lungs, liver, and spleen. Miliary tuberculosis is present in about 2% of all reported cases of tuberculosis and accounts for up to 20% of all extra-pulmonary tuberculosis cases.
A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended from a single mutated cell (monoclonality), as would typically define a benign neoplasm/tumor. Despite this, many hamartomas are found to have clonal chromosomal aberrations that are acquired through somatic mutations, and on this basis the term hamartoma is sometimes considered synonymous with neoplasm. Hamartomas are by definition benign, slow-growing or self-limiting, though the underlying condition may still predispose the individual towards malignancies.
A craniopharyngioma is a rare type of brain tumor derived from pituitary gland embryonic tissue that occurs most commonly in children, but also affects adults. It may present at any age, even in the prenatal and neonatal periods, but peak incidence rates are childhood-onset at 5–14 years and adult-onset at 50–74 years. People may present with bitemporal inferior quadrantanopia leading to bitemporal hemianopsia, as the tumor may compress the optic chiasm. It has a point prevalence around two per 1,000,000. Craniopharyngiomas are distinct from Rathke's cleft tumours and intrasellar arachnoid cysts.
Sparganosis is a parasitic infection caused by the plerocercoid larvae of the genus Spirometra including S. mansoni, S. ranarum, S. mansonoides and S. erinacei. It was first described by Patrick Manson in 1882, and the first human case was reported by Charles Wardell Stiles from Florida in 1908. The infection is transmitted by ingestion of contaminated water, ingestion of a second intermediate host such as a frog or snake, or contact between a second intermediate host and an open wound or mucous membrane. Humans are the accidental hosts in the life cycle, while dogs, cats, and other mammals are definitive hosts. Copepods are the first intermediate hosts, and various amphibians and reptiles are second intermediate hosts.
Tuberculous meningitis, also known as TB meningitis or tubercular meningitis, is a specific type of bacterial meningitis caused by the Mycobacterium tuberculosis infection of the meninges—the system of membranes which envelop the central nervous system.
Hemangioblastomas, or haemangioblastomas, are vascular tumors of the central nervous system that originate from the vascular system, usually during middle age. Sometimes, these tumors occur in other sites such as the spinal cord and retina. They may be associated with other diseases such as polycythemia, pancreatic cysts and Von Hippel–Lindau syndrome. Hemangioblastomas are most commonly composed of stromal cells in small blood vessels and usually occur in the cerebellum, brainstem or spinal cord. They are classed as grade I tumors under the World Health Organization's classification system.
Thyroid nodules are nodules which commonly arise within an otherwise normal thyroid gland. They may be hyperplastic or tumorous, but only a small percentage of thyroid tumors are malignant. Small, asymptomatic nodules are common, and often go unnoticed. Nodules that grow larger or produce symptoms may eventually need medical care. A goitre may have one nodule – uninodular, multiple nodules – multinodular, or be diffuse.
A lung nodule or pulmonary nodule is a relatively small focal density in the lung. A solitary pulmonary nodule (SPN) or coin lesion, is a mass in the lung smaller than three centimeters in diameter. A pulmonary micronodule has a diameter of less than three millimetres. There may also be multiple nodules.
Aponeurotic fibroma, also known as calcifying aponeurotic fibroma, and juvenile aponeurotic fibroma is characterized by a lesion that usually presents as a painless, solitary, deep fibrous nodule, often adherent to tendon, fascia, or periosteum, on the hands and feet. The World Health Organization in 2020 reclassified aponeurotic fibroma nodules as a specific benign type of the fibroblastic and myofibroblastic tumors. Aponeurotic fibromas are diagnosed based on histopathology and treated by surgical excision. They are more common in males than females.
Pineoblastoma is a malignant tumor of the pineal gland. A pineoblastoma is a supratentorial midline primitive neuroectodermal tumor. Pineoblastoma can present at any age, but is most common in young children. They account for 0.001% of all primary CNS neoplasms.
A malignant chondroid syringoma is a very uncommon cutaneous (skin) condition characterised by an adnexal eccrine tumour.
Bonnet–Dechaume–Blanc syndrome, also known as Wyburn-Mason syndrome, is a rare congenital disorder characterized by arteriovenous malformations of the brain, retina or facial nevi. The syndrome has a number of possible symptoms and can, more rarely, affect the skin, bones, kidneys, muscles, and gastrointestinal tract. When the syndrome affects the brain, people can experience severe headaches, seizures, acute stroke, meningism, and progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.
A brain metastasis is a cancer that has metastasized (spread) to the brain from another location in the body and is therefore considered a secondary brain tumor. The metastasis typically shares a cancer cell type with the original site of the cancer. Metastasis is the most common cause of brain cancer, as primary tumors that originate in the brain are less common. The most common sites of primary cancer which metastasize to the brain are lung, breast, colon, kidney, and skin cancer. Brain metastases can occur months or even years after the original or primary cancer is treated. Brain metastases have a poor prognosis for cure, but modern treatments allow patients to live months and sometimes years after the diagnosis.
Computed tomography of the head uses a series of X-rays in a CT scan of the head taken from many different directions; the resulting data is transformed into a series of cross sections of the brain using a computer program. CT images of the head are used to investigate and diagnose brain injuries and other neurological conditions, as well as other conditions involving the skull or sinuses; it used to guide some brain surgery procedures as well. CT scans expose the person getting them to ionizing radiation which has a risk of eventually causing cancer; some people have allergic reactions to contrast agents that are used in some CT procedures.
Intracranial epidermoid cysts develop in the early embryonic phases. The cysts develop when epithelial cells are confined with cells that form the brain.
A melanocytoma is a rare pigmented tumor that has been described as a variant of the melanocytic nevus and is a derivative of the neural crest. The term "melanocytoma" was introduced by Limas and Tio in 1972.
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