Unilocular retroperitoneal cyst of mesothelial origin presenting as a renal mass.

We report the first 2 cases, to our knowledge, of retroperitoneal cysts with features of mesothelial differentiation that clinically mimic renal masses. The first lesion occurred in a 71-year-old man who presented with flank pain. Ultrasound and magnetic resonance imaging studies showed a unilocular cystic structure arising from the upper pole of the left kidney. The second lesion was in a 44-year-old woman who presented with left flank pain. Imaging studies revealed an 8-cm hemorrhagic cyst at the lower pole of the left kidney. Histologic examination of the nephrectomy specimens in each case revealed a unilocular cyst with intracystic and pericystic hemorrhage. In each case, the cyst was lined by a single layer of cells with ample eosinophilic cytoplasm and benign nuclear features without mucinous or müllerian differentiation. Histochemical staining showed Alcian blue positivity on the cell surface, which was sensitive to hyaluronidase digestion. Intracytoplasmic mucin, however, was not detected. Immunostaining showed that the cyst lining cells were positive for keratin, vimentin, HBME-1, WT1, and thrombomodulin but negative for carcinoembryonic antigen, B72.3, Leu-M1, and BerEP4. The first case was positive for calretinin, whereas the second was negative. These findings support the mesothelial nature of the cysts.

Prostatic abscess due to Histoplasma capsulatum in a patient with the acquired immunodeficiency syndrome.

Disseminated histoplasmosis is a systemic fungal infection that may occur in previously healthy or immunocompromised patients. The condition is being recognized with increasing frequency in persons infected with the human immunodeficiency virus. The most common organs involved include the lung, bone marrow, lymph nodes, liver, adrenals and central nervous system, with genitourinary involvement being exceedingly unusual. We describe a Histoplasma capsulatum prostatic abscess occurring after therapy for pulmonary histoplasmosis in a patient with the acquired immunodeficiency syndrome. The prostate may be a difficult focus from which to eradicate disseminated fungal infection in immunocompromised patients.

Decreased activity of Reiter's syndrome after urethrectomy.

Reiter's syndrome is a chronic rheumatic disease that develops after infective urethritis or gastroenteritis and has a strong association with the HLA-B27 antigen. How these factors interact remains unclear. We present a patient with Reiter's syndrome who exhibited 2 novel features: unusually severe urethritis that produced strictures requiring surgery, and dramatic regression of his rheumatic manifestations following a urethrectomy.

Management of acute hydronephrosis of pregnancy by ureteral stenting: risk of stone formation.

Acute hydronephrosis of pregnancy has long been managed with ureteral stenting. Although many articles have been published recently concerning stent incrustation none has addressed the etiology. We report a case of accelerated incrustation due to the hypercalciuric state of pregnancy. We propose conservative management with hydration, calcium restriction and close monitoring for infections and stone debris. Antibiotic suppression and stent changes should not be used routinely but rather they should be individualized.

Localization of ectopic pheochromocytomas by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was utilized to localize ectopic pheochromocytomas in two patients. In both cases, MRI proved superior to computed tomography. Differentiation from surrounding tissue was excellent. MRI permits spatial localization and by assessment of signal contrast intensity provides a suggestion as to the characteristics of the tumor without the use of invasive procedures or intravenous injections. MRI should be considered as an alternative to computed tomography when evaluating patients with a suspected pheochromocytoma.