A 45-year-old male with no remarkable history presented with loss of appetite and a 40 lb weight loss. A CT scan of the abdomen was obtained, revealing a thickened mesentery. Figures 1 and 2 are from the radiologic workup during his hospital admission. A biopsy with 20 G needle aspiration was performed.
CASE SUMMARY:
A 45-year-old male with no remarkable history presented with
loss of appetite and a 40 lb weight loss. A CT scan of the abdomen
was obtained, revealing a thickened mesentery. Figures 1 and 2 are
from the radiologic workup during his hospital admission. A biopsy
with 20 G needle aspiration was performed. What is the most likely
diagnosis?
DIAGNOSIS:
Omental cryptococcosis related to HIV infection
DISCUSSION:
Cryptococcosis is a subacute or chronic fungal infection. The
organism, Cryptococcus neoformans, is an encapsulated yeast-like
fungus that has been found in infected pigeon droppings with
airborne dispersion. The infection is acquired via the respiratory
route, with a primary focus in the lung. Characteristically, it
then spreads to the central nervous system. Additionally, bone and
skin lesions are seen in up to 10% of cases. Cutaneous lesions
appear as acneiform pustules or granulating ulcers. Other, more
rare sites of infection are the breast, adrenal glands, kidney,
prostate, liver, heart, and thyroid. The primary pulmonary
infection may be minimal, with little or no symptoms, and may
regress spontaneously. Cryptococcosis with no detectable pulmonary
lesions, even at autopsy, has been seen, as was the case with our
patient. Chest x-rays of the patient showed no abnormality.
Subsequently, the patient was found to have C. neoformans in his
cerebrospinal fluid.
Reports of abdominal CT findings in patients with HIV infection
and fungal infection are few. Radin reported on abdominal findings
in HIV positive patients with fungal infections, including
cryptococcosis, with CT scans showing splenomegaly, enlarged lymph
nodes, and hepatomegaly.1 Infiltration of the mesentery was not
seen in Radin's series. Additionally, one reported case of
histoplasmosis involving the omentum in an AIDS patient is noted in
the radiological literature.2 There also has been one reported case
of omental cryptococcoma in pathology literature in an otherwise
healthy young man with no underlying illnesses.3
In non-AIDS patients, thickened omentum can be caused by
neoplasms, most commonly due to lymphoma and metastases. Peritoneal
cavity infection secondary to ruptured viscus or secondary to
blood- or lymphatic-borne infection also can produce thickening of
mesentery, and trauma adjacent to or involving the mesentery can
produce infiltration and thickening of the omentum.4
References
1. Radin R: HIV Infection: Analysis in 259 consecutive patients
with abnormal abdominal CT findings. Radiology 197:712-722,
1995.
2. Alterman DD, Cho KC: Histoplasmosis involving the omentum in
an AIDS patient: CT demonstration. J Comput Assist Tomogr
12:664-665, 1988.
3. Chong PY, Panabokke RG, Chew K: Omental cryptococcoma. Arch
Path Lab Med 110:239-241, 1986.
4. Ruess L, Frazier A, Sivit C: CT of the mesentery, omentum and
peritoneum in children. Radiographics 15:89-104, 1995.
Prepared by Ruth Polan, MD and Bernard Gero, MD, Los Robles
Radiology Associates, Los Robles Regional Medical Center, Thousand
Oaks, CA.