Mediastinal
Granulomatous Histoplasmosis
presented
by
Christoph
Lange, M.D., Ph.D.-ID Fellow
Michael
M. Lederman, M.D.-ID Attending
Case
Report
A 20 year old University student with
no significant past medical history developed fever, chills,
shortness of breath and a dry cough five days prior to admission. He
presented two days later to an emergency room and was thought to
have a viral, "flu-like" illness. He was treated
symptomatically. The chest X-ray (Fig. 1a) was unremarkable. A
leucocytosis of 17.4 x109/L with 80% segmented neutrophils and 4%
band-forms on the differential was present. The symptoms persisted
and he presented again to the emergency room the next day. The
clinical examination, chest X-ray (Fig. 1b) and laboratory values
were repeated. He now had a leucocytosis of 20.3 x109/L with
progressive left shift (71% segmented neutrophils and 21%
band-forms). The repeat chest X-ray was not compared with the
previous film. He was again not admitted, but treated with
Levofloxacin for a presumed community-acquired pneumonia. He
remained febrile, the dry cough worsened and he developed substernal
chest pain unrelieved by oral ketorolac. Two days after his last
visit to the emergency room he presented to the student health
clinic, where respiratory stridor was noted. A repeat chest X-ray
(Fig. 1c) showed widening of the upper mediastinum. A computed
tomography (CT) scan of the chest revealed an anterior mediastinal
mass (Fig. 2). The patient was admitted to the hospitalīs oncology
ward with a presumptive diagnosis of malignancy.
Five months prior to admission he had
traveled to Indonesia, spending ten days at a beach resort. Two
months prior to admission he went to a gardening center in Columbus,
Ohio and purchased two hydrocultured orchids for his apartment in
Cleveland/Ohio. He changed the treebark-substrate of the orchids
three weeks prior to his admission because it was covered by mold.
On the day of admission a CT guided
fine needle aspiration biopsy of the anterior mediastinal mass was
performed. The histopathological examination showed fragments of
fibroadipose tissue and collections of mature appearing lymphocytes.
Neoplastic cells were not seen. A bone marrow aspirate showed a
normocellular bone marrow with granulocytic hyperplasia and
increased mega-caryocytes. Granulomas were not seen. Anterior
mediastinoscopy yielded necrotic tissue and pus. Gram stain of the
pus showed 4+ granulocytes, 4+ Gram negative rods and 1+ Gram
positive cocci in chains. Aerobic cultures grew Streptococcus
milleri, anaerobic cultures remained sterile. The histopathological
examination revealed granulomatous lymphoid tissue (Fig. 3) with
multinucleated giant cells (Fig. 4) and numerous silver staining
organisms suggestive of Histoplasma capsulatum (Fig. 5).
Shortly after admission the patient
received one dose of dexamethasone 10mg i. v. followed by 4mg every
8 hours for one day for a presumed malignancy related
superior-vena-cava-syndrome. Antibiotic treatment was started with i.
v. Amphotericin B at 0.5mg/kg daily, Clindamycin 600mg Q6hrs and
Ampicillin 2g Q4hrs. The mediastinoscopy site was left open for
continuous drainage of the abscess. The patient became afebrile in
two days. The respiratory symptoms resolved completely in one week.
Repeat chest CT one week after admission showed a marked decrease in
the size of the mediastinal mass. Intravenous therapy was continued
for ten days. The patient was then discharged on oral Itraconazole.
No further complications occurred. He has fully recovered on a six
months course of Itraconazole 200mg qd.
The histoplasma urinary antigen was
negative on the day after admission and at discharge from the
hospital. Histoplasma antibodies to the mycelial and yeast phase by
complement fixation were present when tested three month later with
a titer of 1:32 and 1:16 respectively.
Although attempts to culture
Histoplasma capsulatum from the orchids' new substrate failed
because the cultures were rapidly overgrown by molds, we suspect
that Histoplasma conidia were inhaled by the patient when he changed
the molded treebark-substrate three weeks prior to his admission.
Histoplasma capsulatum is a soil
based fungus with a broad distribution around the Ohio- and
Mississippi-river valleys (1). Although most primary infections are
clinically unrecognized, immunocompetent hosts can develop acute
symptomatic pulmonary histoplasmosis seven to 21 days after
inhalation of conidia from microfoci, like tree-bark or wood, bird-
or bat feces (2, 3). Clinical symptoms include high grade fever,
chills, headache, non productive cough, substernal chest pain and,
with lesser frequencies myalgia, weakness and fatigue (4, 5).The
disease may be complicated by mediastinal granuloma or fibrosis (6).
Cervical or mediastinal abscesses as a complication of
histoplasmosis are rare (7, 8). Since the radiological findings and
clinical presentation resemble mediastinal malignancies, initial
misdiagnosis is frequent (9, 10). Superinfection of a mediastinal
histoplasma granuloma has previously been described only once in the
literature (11), involving Streptococcus mitis and Bacteroides
melaninogenicus, organisms similar to those in this case, suggesting
a common pathogenic pathway by lymphogenous spread from the upper
respiratory tract. There are no data from clinical trials available
comparing treatment with Amphotericin B, Itraconazole or
Ketoconazole for complicated acute pulmonary histoplasmosis. Initial
treatment of severely ill patients with Amphotericin B 0,5 mg/kg
daily followed by oral Itraconazole 200 mg p.o. daily for four to
six month is currently recommended (12).
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Figures
|
A |
B |
C |
|
Figure
1: Sequential chest X-rays taken three days (a) and two
days (b) prior to admission and on the day of admission (c)
show increased widening of the mediastinum
|
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References
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