Aspergillus Fumigatus

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Pulmonary Pseudoaneurysm Due to Aspergillus Fumigatus in a Breast Cancer Patient

Dominic M. Castellano, BS,University of South Florida College of Medicine,

Tampa, Fla., N. Greene, MD,University of South Florida College of Medicine,

Tampa, Fla., H. Lee Moffitt Cancer Center and Research Institute, Tampa, Fla.,

Lary A. , MD,University of South Florida College of Medicine, Tampa,

Fla., Ramon L. Sandin, MD,University of South Florida College of Medicine,

Tampa, Fla., H. Lee Moffitt Cancer Center and Research Institute, Tampa, Fla.,

A. Muro-Cacho, MD, PhD, University of South Florida College of Medicine,

Tampa, Fla.

[infect Med 16(3):201-204, 1999. © 1999 SCP Communications, Inc.]

Abstract

Aspergillus molds can cause life-threatening infections, especially in

immunocompromised patients. When Aspergillus species invade blood vessels, they

cause tissue infarction and distal necrosis. At times, these invasive infections

weaken arterial walls sufficiently to cause an aneurysm. However, this type of

aneurysm is rare; it has been reported in only 2.6% of 338 aneurysms during a

50-year period. Arteriography and MRI are the diagnostic techniques of choice to

confirm a pseudoaneurysm.

Introduction

In immunocompromised patients, Aspergillus species molds are capable of causing

life-threatening infections. We report on a patient with metastatic breast

cancer who developed a pseudoaneurysm of the right pulmonary artery due to

infection with Aspergillus fumigatus.

Case Report

A 42-year-old white woman underwent high-dose chemotherapy followed by

autologous bone marrow transplantation for recurrent metastatic breast

carcinoma. Despite administration of broad-spectrum antibiotics, high fevers

developed while neutropenic, and a pulmonary infiltrate appeared on chest

radiograph. Chest CT demonstrated a cavitary, peripheral, right-upper-lobe mass

as well as a second, central, 3.2cm-diameter right lung mass adjacent to the

proximal pulmonary artery (Fig. 1). A fumigatus was cultured from bronchial

washings.

Treatment with amphotericin B lipid complex 5mg/kg/day was begun. Clinically,

the patient improved, but low-grade fever persisted. One month after the initial

CT, repeat chest CT demonstrated that the peripheral lesion was smaller but the

central lesion remained unchanged (Fig. 2). In addition, the adjacent pulmonary

artery, opacified by contrast media, was somewhat larger.

One week after the second CT, the patient experienced light, daily hemoptysis of

a few streaks of blood and an occasional clot. A third chest CT a week later

showed that the peripheral mass was much smaller, but the central lesion now

measured 4.2cm in diameter and was almost completely filled with contrast media

(Fig. 3). These results strongly suggested a mycotic false aneurysm of the right

pulmonary artery.

Because of suspected impending rupture of this pseudoaneurysm, the patient

underwent urgent surgery the following day. A right pneumonectomy was performed

because the false aneurysm was located proximally at the second division of the

pulmonary artery. At the time of surgery, a large, pulsatile mass was palpable

centrally in the right lung. The specimen sent to pathology showed several

fibrotic patches and small nodules on the lung parenchyma. Following fixation

for 24 hours, the lung was sectioned along the pulmonary artery. An area of

aneurysmal dilatation was noted at the major bifurcation surrounded by marked

hemorrhage and inflammation, with a thrombus within a vessel in continuity with

the larger pulmonary artery (Fig. 4). A second cavitary lesion was also seen

along the outer aspect, containing yellow-brown material. Tissue from the lung

parenchyma and pleural fluid failed to grow an organism on culture, although

smears from the tissue showed abundant septated fungal hyphae.

Microscopic pathologic sections showed invasive pulmonary fungal infection with

destruction of bronchial airways, vascular invasion of 1 of the pulmonary artery

branches (Fig. 5), and thrombotic occlusion of the lumina. Extensive necrotizing

granulomata and focal pulmonary hemorrhage were also present. Elastin stains

revealed invasion of the vessel wall by the necrotizing process (Fig. 6).

The patient recovered uneventfully and was discharged 1 week after surgery. As

an outpatient, she completed 6 additional weeks of treatment with amphotericin B

lipid complex 5mg/kg/day followed by 6 weeks of itraconazole 200mg twice daily.

However, 9 months after completion of therapy, the patient died from failure to

thrive and multiorgan dysfunction. There was no evidence of prior Aspergillus

infection.

Discussion

Aspergillus species are ubiquitous molds that are capable of causing

life-threatening infections in immunocompromised patients. Most infections in

humans are caused by A fumigatus, followed in frequency by Aspergillus flavus

and Aspergillus niger.[1]

Aspergillus species tend to invade blood vessels and cause tissue infarction and

distal necrosis. These invasive infections occasionally weaken an arterial wall

sufficiently to cause an aneurysm. The term " mycotic aneurysm " is currently used

to describe an invasion of an arterial wall by any microorganism, which includes

bacteria or fungi.[2] However, this type of aneurysm is rare, reported in only

2.6% of 338 aneurysms during a 50-year period.[3] The great majority of patients

with invasive Aspergillus infections are severely immunocompromised, either from

profound leukopenia secondary to cytotoxic chemotherapy[4-7 ]or from high-dose

corticosteroid therapy, especially when combined with other immunosuppressive

agents in recipients of organ transplants.[8-12]

In our patient, the false aneurysm was manifested approximately 20-25 days from

the onset of symptoms. Hemoptysis was an important clue to an impending aneurysm

rupture. However, hemoptysis is a common occurrence in Aspergillus pneumonia

because of angioinvasion, thrombosis, and tissue infarction.

Invasive aspergillosis usually appears radiographically as 1 or more pulmonary

nodules, which in the neutropenic patient may be solid with a faint radiopaque

halo surrounding it (ie, the " halo sign " ). When an adequate neutrophil count is

present, the lesion usually becomes cavitary with a central, ball-like density,

giving the appearance of an air-crescent on CT (ie, the " air-crescent sign " )

(Fig. 7). The lesion is caused by contraction of necrotic tissue in the

periphery of the lesion, some of which is phagocytized by macrophages, leaving a

central sequestrum of necrotic tissue surrounded by air.

Pulmonary artery aneurysms or pseudoaneurysms are best demonstrated by pulmonary

arteriogram or MRI. CT can presumptively demonstrate a larger central aneurysm,

particularly if the patient has a large bolus of contrast media, injected at an

appropriate time, that opacifies the pulmonary arteries. The saccular false

aneurysm in our patient was readily demonstrated by CT, which showed an

enlarging, contrast-media-filled central lung lesion contiguous with the

proximal pulmonary artery. The definitive diagnosis of a fungal false aneurysm

was established by a pathologic evaluation of the surgical specimen.

A transthoracic biopsy of a suspected fungal pulmonary lesion should be

performed only when there is some certainty that it is not a false aneurysm.

This is imperative because biopsy could rupture the aneurysm, leading to death.

Once the diagnosis of a pulmonary false aneurysm is confirmed, urgent surgical

resection is mandatory to prevent its rupture.

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