We report a case in which ARDS was the presenting manifestation of testicular choriocarcinoma with numerous metastases to the lungs. We also review the literature on other cases in which ARDS developed as a result of neoplastic infiltration of the lungs and stress the fact that it may be indistinguishable from ARDS from other causes. Because potentially effective chemotherapy for the neoplastic processes most commonly involved (ie, germ cell tumors, acute leukemia and lymphoma) is available, we emphasize the importance of considering a neoplastic disorder in the differential diagnosis of cases of otherwise unexplained ARDS. Early accurate diagnosis could conceivably result in an improved outcome in these cases.
Adult respiratory distress syndrome is a form of acute respiratory failure which develops as a result of acute, severe, diffuse injury to the alveolar epithelium and pulmonary microvascular endothelium. A variety of disorders have been associated with its development. We report the first case, to our knowledge, in which ARDS was the presenting manifestation of primary choriocarcinoma of the testis associated with numerous metastases to the lungs.
A 32-year-old white man, previously healthy except for a history of chronic schizophrenia, was transferred from a state mental hospital with a one-day history of fever, blood-tinged sputum and dyspnea. Physical examination revealed an agitated man with an oral temperature of 38.3 [degrees] C, a respiratory rate of 42 breaths per minute, a pulse rate of 130 beats per minute and blood pressure of 120/70 mm Hg. Lung examination revealed diffuse crackles. The testicles were bilaterally symmetrical and without masses. The WBC count was 12,700/cu mm; hemoglobin value, 9.3 g/dl; and hematocrit value, 28.8 percent. Chest roentgenogram showed bilateral pulmonary infiltrates without cardiomegaly. Room air ABG values included a [PO.sub.2] of 57 mm Hg; [PCO.sub.2] of 23 mm Hg; and a pH level of 7.50. Electrocardiogram was normal except for a sinus tachycardia of 130/min. A diagnosis of pneumonia was made and treatment with nasal oxygen and intravenous erythromycin and cefuroxine was begun. Later that day he became diaphoretic and increasingly dyspneic. Repeat chest roentgenogram (Fig 1) revealed worsening pulmonary infiltrates with some areas having a somewhat nodular appearance. Arterial oxygen pressure on 4 liters of nasal oxygen was 27 mm Hg. The patient was intubated and placed on mechanical ventilation, high [FIO.sub.2] and PEEP. His [PaO.sub.2] improved to 153 mm Hg. Gram stain of an endotracheal sputum specimen revealed moderate polymorphonuclear and red blood cells but no organisms. The next day his temperature was 39.5 [degrees] C; the WBC count was 22,200/cu mm; and he had developed grossly bloody sputum. Bronchoscopy revealed no active bleeding and minimal secretions (negative for organisms including Pneumocystis carinii). The [PaO.sub.2] was 75 mm Hg on an [FIO.sub.2] of 0.60 and 8 cm [H.sub.2]O of PEEP. Because there was no evidence of hemodynamic compromise, a Swan-Ganz catheter was not placed. On the third hospital day, he became hypotensive, progressively hypoxemic and suffered a cardiac arrest from which he could not be resuscitated.
Postmortem examination revealed markedly heavy lungs with a combined weight of 3,500 g. The lungs were studded with numerous well-circumscribed hemorrhagic nodules consistent with a metastatic neoplasm. Microscopic examination showed both syncytiotrophoblastic and cytotrophoblastic elements diagnostic of choriocarcinoma (Fig 2). Lung tissue not involved by tumor showed the exudative phase of diffuse alveolar damage (ie, interstitial edema, hyaline membranes lining alveolar ducts and alveolar spaces, marked alveolar capillary congestion and various degrees of fresh alveolar hemorrhage). The right testicle was essentially replaced by choriocarcinoma but was the same size as the uninvolved left one. The heart was normal with no evidence of dilatation or infarction.
Adult respiratory distress syndrome generally develops in the setting of sepsis, aspiration, shock or some other identifiable disorder.[1-3] In some cases of ARDS, however, the underlying, triggering factor may be obscure.[4,5] In our case, ARDS was the presenting manifestation of metastatic testicular choriocarcinoma. Our patient had the typical clinical characteristics of ARDS. He had the rapid onset of respiratory distress, diffuse crackles on lung examination, bilateral, confluent alveolar infiltrates on chest roentgenogram and progressive arterial hypoxemia refractory to supplemental oxygen therapy. Postmortem examination confirmed the diagnosis of ARDS. The unexpected and previously unreported finding was the presence in the lungs of metastatic choriocarcinoma of the testicle. In many areas the tumor was necrotic and there was extensive hemorrhage. There were no other findings present to explain the patient's ARDS. Although a Swan-Ganz catheter had not been inserted, it has recently been stressed that Swan-Ganz measurements are not a necessary part of the diagnosis of ARDS. Furthermore, since pathologic examination of the heart was normal, it is highly unlikely that heart failure was the cause of his pulmonary edema.
Pulmonary involvement with neoplastic disease is an unusual but recognized cause of ARDS. It has previously been reported in association with metastatic gestational choriocarcinoma, as the presenting feature of diffuse pulmonary lymphoma and as a prominent finding in a case of Mycosis fungoides with lung involvement. In addition, in a group of patients with ARDS who underwent diagnostic open-lung biopsy, nine of 19 patients with a previous diagnosis of malignancy were found to have diffuse tumor infiltration of their lungs (four cases of leukemia and one case each of lymphoma, angiosarcoma, histiocytosis, adenocarcinoma and choriocarcinoma). Another report described three patients with previously undiagnosed acute myelogenous leukemia who presented with ARDS due to diffuse leukemic infiltration of the lungs.
The pathogenesis of widespread alveolar-capillary membrane damage associated with metastatic tumor is speculative. In the case of choriocarcinoma the pulmonary metastases are often hemorrhagic. This presumably reflects the tumor cell's capacity to directly invade, erode and destroy blood vessels. It is also possible that some products elaborated by the tumor cells can injure blood vessels without direct tumor invasion.
The prime importance of this case is the recognition that although uncommon, metastatic pulmonary tumors can cause a clinical picture of ARDS indistinguishable from other causes. Although rare, choriocarcinoma and other trophoblastic tumors should be considered as possible etiologies of ARDS. This is particularly true in young patients without other obvious explanations, especially if the infiltrates on chest roentgenogram appear somewhat nodular. In a pregnant woman with unexplained ARDS, hydatiform mole or gestational choriocarcinoma should always be considered. Other malignancies may also present with or subsequently be complicated by the development of ARDS. In patients with either an established diagnosis or suggestive findings of a malignant disorder (eg, lymphadenopathy) diffuse pulmonary tumor infiltration should be considered in the differential diagnosis. Bronchoalveolar lavage and/or transbronchoscopic lung biopsy may be diagnostic. In selected cases, open-lung biopsy may be warranted despite the potential morbidity. The importance of making a specific diagnosis in ARDS should not be underestimated. Supportive treatment alone is generally ineffective unless the underlying disorder is reversed or controlled.[13,14]
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