Browsing by Author "Al-Obaidy, Khaleel"

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    Immunohistochemical characteristics of Renomedullary interstitial cell tumor: a study of 41 tumors with emphasis on differential diagnosis of mesenchymal neoplasms
    (Elsevier, 2018) Lu, Zhichun; Al-Obaidy, Khaleel; Cheng, Liang; Perry, Kyle D.; Grignon, David J.; Williamson, Sean R.; Pathology and Laboratory Medicine, School of Medicine
    Renomedullary interstitial cell tumors (RMICT) are almost always incidentally identified either at autopsy or resection of the kidney for other reasons. However, rare cases have been reported which are large, resulting in a clinical mass. The immunohistochemical phenotype of usual, incidental RMICT using modern soft tissue tumor markers in is largely unknown, however, providing little information to aid in classification of larger or atypical tumors. We retrieved 41 RMICTs from 36 patients, and studied pathologic characteristics including morphology, immunohistochemistry (S100, keratin AE1/AE3, smooth muscle actin, desmin, estrogen and progesterone receptors, calponin, CD34, CD35), and histochemical staining. Data collected included age, gender, tumor size, laterality, and indication for kidney examination. RMICTs (n = 41) were identified in 23 men and 13 women, with mean age 57 years (range 24–83), tumor sizes ranged from <1 to 13 mm (median 4 mm). Kidneys were resected for 32 tumors, 1 chronic pyelonephritis, 1 trauma, and 2 autopsies. All (41, 100%) had entrapped renal tubules, 5 (12%) of which included cystic or dilated tubules. Most (35, 85%) had collagenous fibers, all of which were negative for Congo red. RMICT demonstrates a largely negative immunohistochemical phenotype with weak to moderate labeling for smooth muscle actin and calponin that is substantially less than myofibroblastic lesions. Positive staining for estrogen and progesterone receptor is common (61%), which could overlap with mixed epithelial and stromal tumor and other entities; however, staining is typically weak. CD34 is usually negative, with occasional weak labeling, in contrast to solitary fibrous tumor.
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    Localized amyloidosis of the prostatic urethra mimicking urothelial carcinoma
    (e-Century Publishing, 2021-10-15) Collins, Katrina; Al-Obaidy, Khaleel; Warmke, Laura; Cary, Clint; Chen, Shaoxiong; Pathology and Laboratory Medicine, School of Medicine
    Amyloidosis is a disease characterized by extracellular deposition of amyloid protein fibrils in tissues. It rarely involves the urethra with just over 50 cases reported in the English language literature. We report a case of urethral amyloidosis that mimicked urothelial carcinoma clinically. The patient is a 69-year-old male who presented to the emergency department with shortness of breath. An abdominal CT scan demonstrated a right hydronephrotic kidney and a large, predominantly hyperdense lesion, presumed to be hematoma largely occupying the urinary bladder. Pan-cystoscopy revealed a 6 cm bladder mass involving the prostatic urethra displacing the right ureteral orifice, which was biopsied. Histologic examination showed numerous osteoclast-type giant cells, with areas of extensive calcification and multifocal ossification interspaced by large deposits of amorphous eosinophilic material. Amyloid deposition was confirmed by Congo red and sulfated Alcian blue stains. Light chromatography tandem mass spectrometry was performed and detected multiple types of proteins including serum amyloid P component, apolipoprotein A4, and apolipoprotein E; however, a dominant amyloid type was not identified. The patient had no history of infection or localized inflammation. Further investigations for systemic amyloidosis were all negative. Amyloidosis of the urethra is extremely rare and may either be localized, idiopathic or a manifestation of systemic amyloidosis. Physicians among various specialties, including urologists, pathologists and radiologists should be aware of this rare entity, as this lesion may be easily mistaken for malignancy further emphasizing the importance of tissue diagnosis before definitive surgery. Long-term follow-up in the absence of symptoms may not be required.