21. A 35-year-old HIV-positive man (CD4+ count 150 - highsky

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21. A 35-year-old HIV-positive man (CD4+ count
150/mm3) is seen in the ED with right-sided
chest pain. The patient has become progressively
dyspneic over the past few days. Suddenly,
30 minutes ago he noticed a sharp pain
in his chest associated with shortness of breath.
His temperature is 37.7° (99.9°F), blood pressure
is 128/84 mm Hg, pulse is 102/min and
regular, respiratory rate is 25/min, and oxygen
saturation is 90% on room air. Physical examination
reveals diminished right-sided breath
sounds and hyperresonance. Jugular venous
distention is 5 cm and there is no tracheal deviation.
ECG shows sinus tachycardia. X-ray of
the chest shows a right-sided pneumothorax
occupying approximately 10% of the right thoracic
cavity. Which of the following etiologies
most likely caused this patient™s presentation?
(A) Intravenous drug use
(B) Kaposi™s sarcoma
© Mycobacterium tuberculosis
(D) Pneumocystis jiroveci (formerly carinii)
pneumonia
(E) Toxoplasmosis

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DD

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dd

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21. The correct answer is D. Pneumothorax is an
uncommon but potentially fatal complication
of HIV believed to occur in 2“6% of HIV patients
at some point during their infection.
More than 80% of the cases of pneumothorax
in HIV patients occur in conjunction with
Pneumocystis jiroveci pneumonia. Extensive
tissue invasion within the alveolar interstitium
is common in severe P. jiroveci pneumonia,
Chapter 14: Pulmonary ¢ Answers 427
and may be an important factor in causing
necrosis and subsequent pneumothorax. Patients
with pneumothorax present with the
sudden onset of unilateral pleuritic chest pain
and dyspnea. Physical examination can reveal
decreased or absent breath sounds, hyperresonance,
and decreased tactile fremitus on the
affected side.
Answer A is incorrect. Pneumothorax may result
from unsuccessful attempts to inject drugs
into the central circulation via the subclavian
and jugular veins (œpocket shots). However,
there is no evidence that this patient uses injection
drugs.
Answer B is incorrect. Kaposi™s sarcoma is a
vascular tumor arising from infection with human
herpesvirus 8. Kaposi™s sarcoma is the
most common tumor arising in patients with
AIDS and is 20,000 times more common in
AIDS patients than in the general population.
While Kaposi™s sarcoma does occur in conjunction
with pneumothorax in HIV patients,
it is not as frequent as Pneumocystis jiroveci
pneumonia.
Answer C is incorrect. Mycobacterium tuberculosis
is a mycobacterial opportunistic infection
encountered in AIDS. Mycobacterium tuberculosis
has no association with
pneumothorax in HIV patients.
Answer E is incorrect. Toxoplasmosis is a protozoan
opportunistic infection encountered in
AIDS. Toxoplasmosis has no association with
pneumothorax in HIV patient

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