INTRODUCTION Granulomatous inflammation is a distinctive ...

non invasive investigations are not specific, doesn’t lead to a solid management decisions and are
time consuming on the other hand. Thus, the gold standard for definite diagnosis for most of these
disorders is tissue biopsies and cultures, which is hindered by technical obstacle.
Even if a definite diagnosis is reached, treatment studies on neurological manifestations of
granulomatous diseases are lacking. Treatment decisions are either following the guidelines of
management of the systemic side of these disorders, or are lacking clear guidelines due to absence
of controlled studies or controversy on lines of management.
It is worth mentioning that the role of epidemiological distribution is of ultimate importance in the
diagnosis of such overlapping conditions. This can be applied clinically when atypical cases are
met to prioritize the differential diagnosis and the subsequent investigational panel and treatment
plan. For example TB is endemic in developing countries especially in India, this is due to lack of
eradication programs, increased prevalence of HIV, and poor sanitation. Yet recently it started
spreading again in developed countries with migration. Cysticercosis is also prevalent in India and
many developing countries due to poor sanitation. Hydatid disease is prevalent in middle east, east
Africa, parts of Russia and South America. Bilharziasis is endemic in parts of Asia, South
America and Africa including Egypt, while absent in Europe and North America. Although some
types of fungal infections are present world wide, such as candida and Cryptococcus, yet others
have a limited geographical distribution like Aspergillosis which is prevalent in the tropical zones
and Mediterranean, and coccidioidomycosis is present only in Arizona in the United States of
America.
Even the non infectious granulomas have a rather clinically significant pattern of distribution. For
example, sarcoidosis is prevalent in northern Europe while almost absent in China and southern
Asia.
In the last few decades, both the incidence and the prevalence of some of these disorders have
increased. This is directly related to the increased prevalence of immunosuppressive states, due to
the pandemic of HIV infection, use of immunosuppressive drugs, and organ transplantation.
The most common granulomatous disorders encountered in relation to the immune system
condition are TB, Toxoplasmosis, Cryptococcus, candidacies, coccidioidosis, aspergillosis and
mucormycosis. These conditions were thoroughly studied in HIV infected population compared to
other immunosuppressed states, to the extent that the guidelines of HIV treatment is now
recommending prophylactic treatment for many of these disorders according to the immunostatus
of the patient (CD cell count).
Clinically, the above mentioned granulomatous disorders have an overlapping widely varied
clinical presentation. Moreover these symptoms overlap with other CNS neoplastic lesions (e.g.
lymphoma) or other opportunistic infections. Rarely the clinical picture may have some specific
features according to the cause, for example, blindness is common in cryptococcal meningitis,
while acute onset of focal neurologic deficits is more suggestive of aspergillosis, and CNS
candidiasis usually present in the context of systemic affection.
Because of the formentioned confusing clinical presentations we relay on investigations to reach a
reliable diagnosis. The definitive diagnosis of CNS tuberculosis needs to be rapid as the prognosis
differs radically depending on the time of start of treatment. Yet the gold standard (smear,
culture) are time consuming and not sensitive. Lately PCR is showing promising results, with
relatively higher sensitivity compared to culture, rapid, but expensive, technically demanding, and
unavailable in endemic area. In CNS toxoplasmosis radiological studies show multiple brain
enhancing lesions which when combined with positive serology empirical treatment should be
started and if there is no response in 2 weeks, a tissue biopsy should be obtained. As regard fungal