A 27-year-old woman, active polydrug addict, who 15 days before admission started with a dry cough, dyspnoea of progressive intensity, fever, asthenia, anorexia, nausea and vomiting. She had a history of recently diagnosed HIV infection, with unknown immunological and virological parameters. Examination on admission showed cachexia, 40 breaths/min, 120 beats/min. BP: 110/60 mm Hg, thrush, acropacities, bilateral cervical lymphadenopathy less than 1 cm and right supraclavicular 2 cm. Generalised decrease in vesicular murmur and bibasal crackles, systolic murmur II/VI polyfocal, hepatomegaly 2 cm from the costal border and vulvar condylomas. The rest of the somatic and neurological examinations were normal. The following complementary tests were performed on admission: Hb 11.3 g/dL, 6,900 leukocytes/µL (79% segmented, 14% lymphocytes), 682,000 platelets/µL; sodium 119 mmol/L, LDH 603 IU/L, the rest of the autoanalyser values were normal. Baseline arterial blood gases on admission: pH 7.54, pCO2 34.8 mm Hg, pO2 73.4 mm Hg. Chest X-ray showed a right anterior mediastinal mass compressing and displacing the trachea and a bilateral alveolar-interstitial infiltrate. Subsequently, abdominal ultrasound and thoracic, abdominal and pelvic CT scans were performed, showing bilateral axillary lymphadenopathies smaller than one cm, a large mediastinal mass compressing the trachea and superior vena cava, a resolving pulmonary interstitial pattern and thickening of the wall of the intestinal loops with a small amount of free fluid between them. A transthoracic echocardiogram was performed and no abnormalities were found. Treatment was started with cotrimoxazole, levofloxacin and amphotericin-B, despite which he developed progressive respiratory failure, requiring mechanical ventilation. Over the following days, the respiratory failure improved and mechanical ventilation was withdrawn. Subsequently, he presented with a generalised tonic-clonic seizure followed by left hemiparesis; a cranial CT and MRI scan was performed, showing a thick-walled mass with a hypodense centre measuring 4 cm in diameter at the right temporo-parieto-occipital junction. Sulphadiazine, pyrimethamine, folic acid and phenytoin were added to the treatment, which was withdrawn three weeks later due to lack of clinical improvement and reduction of the intracranial lesion. FNA and biopsy of supraclavicular adenopathy were performed and reported as metastasis of undifferentiated malignant tumour of epithelial origin. Later the following results were received: CD4+ lymphocytes: 440/mL, HIV viral load: 25,000 copies/mL, normal alpha-fetoprotein and b-HCG: 650 mIU/mL (normal < 5). Microbiological studies on blood, urine, sputum, brocoaspirate and lymph node puncture were negative for bacteria, mycobacteria and fungi. Staining of respiratory samples was negative for P. carinii (P. jiroveci). Serologies for Toxoplasma, hepatotropic viruses and RPR were negative; cryptococcal antigen was negative.

Diagnosis and evolution: Initially the diagnosis was made of diffuse pneumonia presumably due to P. carinii (P. jiroveci) and probable disseminated lymphoma with mediastinal, cerebral and intestinal involvement. After receiving the results of the lymph node biopsy and tumour markers (alpha-fetoprotein and ß-HCG), the definitive diagnosis was made: extragonadal germ cell tumour with supraclavicular and mediastinal lymph node involvement, and probably cerebral. It was suggested that the patient undergo a tumour extension study and start treatment with polychemotherapy, which she refused, despite being told that the high chemosensitivity of the tumour made it potentially curable. The patient died in another centre several weeks after discharge.