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Zorluk: OrtaInterpreting Imaging Results

A 54-year-old man is evaluated in the hospital for fever and right-sided chest pain. He is currently on day 14 of induction chemotherapy for acute myeloid leukemia. For the past 10 days, his absolute neutrophil count has been consistently below 100/mm³. Over the last 24 hours, he has developed a temperature of 39.2°C (102.6°F), a nonproductive cough, and pleuritic chest pain. Vital signs show a heart rate of 110/min, blood pressure of 115/70 mm Hg, and respiratory rate of 22/min. Oxygen saturation is 94% on room air. Auscultation reveals focal crackles over the right upper lung field. A high-resolution CT scan of the chest without contrast demonstrates a 2.5-cm dense macronodule in the right upper lobe surrounded by a distinct zone of ground-glass attenuation. Based on these imaging findings and the clinical presentation, which of the following is the most likely diagnosis?

  1. Invasive pulmonary aspergillosisCevap
  2. B
    Pneumocystis jirovecii pneumonia
  3. C
    Reactivation of Mycobacterium tuberculosis
  4. D
    Cytomegalovirus pneumonitis
  5. E
    Staphylococcus aureus pneumonia

Cevap

Invasive pulmonary aspergillosis
The correct answer is invasive pulmonary aspergillosis. This patient's history of profound, prolonged neutropenia places him at extreme risk for opportunistic mold infections. The high-resolution CT describes the classic 'halo sign'—a dense pulmonary macronodule surrounded by a rim of ground-glass opacity. This imaging finding is highly suggestive of invasive pulmonary aspergillosis early in its disease course. Pathophysiologically, the solid core corresponds to central fungal proliferation and ischemic tissue infarction, while the surrounding ground-glass halo corresponds to alveolar hemorrhage secondary to fungal angioinvasion (invasion of the local pulmonary vasculature). Recognizing this specific radiographic pattern is critical for initiating prompt antifungal therapy.

Adım Adım Çözüm

1
Evaluate the patient's clinical risk factors based on the history and laboratory data.
The patient has profound and prolonged neutropenia (< 100/mm³ for 10 days) following chemotherapy for hematologic malignancy.
This establishes severe immunosuppression, making the patient highly susceptible to opportunistic infections, especially angioinvasive molds.
2
Analyze the specific findings on the high-resolution chest CT scan.
The imaging shows a dense right upper lobe macronodule surrounded by a distinct zone of ground-glass attenuation.
This combination of features is radiographically defined as the 'halo sign'.
3
Correlate the radiographic 'halo sign' with the underlying pathophysiology and clinical context.
The solid nodule represents fungal proliferation and tissue infarction, while the ground-glass halo represents surrounding alveolar hemorrhage caused by the fungus invading local blood vessels.
This highly specific correlation confirms the most likely diagnosis of invasive pulmonary aspergillosis.

Anahtar Kavram

The 'halo sign' on chest CT (a macronodule surrounded by ground-glass opacity) in a profoundly neutropenic patient is highly indicative of invasive pulmonary aspergillosis, representing fungal angioinvasion and resultant surrounding hemorrhage.
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Interpreting Imaging Results

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