Other
Fungal Infections
Introduction: There
are other, perhaps less known fungal infections that can occur in people with
a normal immune system such as chromomycosis. On the other hand AIDS patients
or those who have a weak immune system like cancer patients or patients who had
transplants and are on immunosuppressants, can develop otherwise rare fungal diseases
such as mucormycosis or phaeohyphomycosis.
Chromomycosis Introduction: Chromomycosis
is a rare fungal infection of the skin of patients with a normal immune system.
It happens usually in the tropics or subtropics. The entry into the body occurs
through small skin wounds in the feet, lower legs or other skin areas. As the
fungi that cause chromomycosis contain melanin, which is pigment laden, the skin
eruptions containing the fungi also appear dark and pigmented. A number of different
species such as Bipolaris, Cladosporium, Phialophora and many others cause chromomycosis.
Signs and Symptoms: The initially isolated skin
lesion enlarge, ulcerate, multiply and for between 4 and 15 years stay locally
confined to an extremity or a regional area of skin. Here is a picture
of a male with chromomycosis of the lower leg. The underlying
lymph vessels and lymph glands get also infected and this can lead to edematous
swelling of the regional area. The affected skin is very itchy. Scratching only
helps to infect the neighboring skin. Eventually cauliflower like skin surface
develops that is pigmented compared to the normal skin. Bacterial superinfection
of scratched open lesions can complicate the clinical picture. Diagnostic
Tests: The diagnosis can be difficult and culture methods and
biopsy and histological analysis are the only reliable means to confirm the clinical
suspicion. A skin specialist likely should be consulted. Treatment:
Itraconazole (brand name: Sporanox) is the treatment of choice,
but will not heal all of the cases. The specialist may use other agents such as
flucytosine (brand name: Ancobon) as additional therapy. If antifungal therapy
does not lead to a cure, the physician may have to use surgical excision as an
additional mode of therapy.
Phaeohyphomycosis If
the skin infection described under "chromomycosis" is invading from
a local infection into the rest of the body, this is called a phaeohyphomycosis.
This is happening a lot more in immunocompromized patients such as in the presence
of AIDS, or in poorly controlled diabetics or patients with cancer.
| Phaeohyphomycosis
-- what's that? |
Step 1: the roots. "pheo"
or "phaeo-" is a term originating from the Greek word "phaios"
meaning dun, dusky or brown."Hyphomycosis" has its roots in the Greek
"hyphe" meaning web and "mykes" meaning fungus. Hyphomycetes
is a species of imperfect fungi that can multiply in the skin (to be contrasted
with imperfect yeast infections such as monilia). |
Step 2: putting it together. "Phaeohyphomycosis"
is a fungus infection with incomplete fungi that form spores and hyphae that are
pigmented, dark brown or black. Most authorities use the term "chromomycosis"
for localized infections of the skin with these pigmented species and the term
"phaeohyphomycosis" for infections of other tissues than the skin with
this fungus (see text). | With phaeohyphomycosis
the pigmented fungi spread to other parts of the body, likely either through the
lymphatic system or through the circulatory system. This way chronic festering
infections of the sinus cavities, bones, joints, lungs, heart valves (=endocarditis),
brain (=brain abscess) or the meningeal membranes (=meningitis) can occur. Also,
there can be nodules or abscesses can show up under the skin, in regional lymph
glands of infected skin or organs. Even internal bleeding can happen when a local
abscess erodes a major blood vessel. Systemic spread like this is facilitated
when the immune system is weak such as in AIDS patients or in patients with cancer
or diabetes out of control. Signs and Symptoms:
Here is a picture of a child
with this condition. Depending on what organ system is involved,
the symptoms change. For instance, with involvement of the heart valves, such
as in endocarditis, depending on the severity there will be circulatory symptoms
with signs of congestive heart failure such as cyanosis (bluish skin discoloration),
shortness of breath, weakness etc. With a lung lesions there might be a cough,
shortness of breath and chest pains. X-rays would show lesions that would be followed
up with further investigations such as bronchoscopy or lung biopsy. Diagnostic
Tests: Biopsies of diseased tissue are sent to the pathologist
who will use special melanin staining techniques to diagnose this condition. Ultrasonic
tests, CT or MRI scan testing as well as regular x-rays are all helpful in assessing
the extent of the disease. Treatment: This can be particularly
difficult to treat and this article
discusses one such case that was difficult to treat.
Mucormycosis
This fungal infection is characterized by irregular shapes of hyphae (thread
like structures) that can be caused by a number of rare fungi (species of Rhizomucor,
Rhizopus and others). It happens mostly in patients whose immune system is compromised
such as in AIDS patients, patients with poorly controlled diabetes in ketoacidosis,
with kidney failure or in patients who receive high doses of corticosteroids or
other immunosuppressive therapy. The most common form of mucormycosis is
an infection inside the nose that spreads to the sinuses and through the bone
into the base of the brain cavity. Associated with this can be excruciating pain
deep underneath the face and in the bones of the sinuses. Headaches, fever, and
a breakdown of the palate bone on top of the roof of the mouth cavity are some
of the possible and more common symptoms. There can be a pussy nasal discharge,
swelling around the eye socket with bone destruction of the bones behind and around
the eye. Here is a picture
of mucormycosis. Superinfection with bacteria can lead to more dangerous
cellulitis around the eye, which could very quickly will spread into the meningeal
membranes, if untreated, and cause meningitis. Occasionally the initial lesions
are found in the lungs, the skin or the GI tract. The diagnosis of this
condition is very difficult and the physician must have a high index of suspicion.
The only positive tests are histological examination of tissue biopsy samples
by an experienced histopathologist. The characteristic irregularly shaped hyphae
are what make the diagnosis. Cultures are not reliable and there is presently
no reliable blood test antibody titer. Treatment is also difficult, as the only
reliable drug that helps is intravenous amphotericin B, but this will not reach
avascular abscessed areas. This means then that affected areas that do not have
a lot of blood vessels need to be surgically explored and any infected material
should be excised until the vascular margin is reached. The remainder of the disease
should then be amenable to the intravenous amphotericin B. Other oral antifungal
antibiotics have not been found to be of benefit (Ref. 1, p. 1223 and 1225). |
