We report a rare case of oncocytic renal cell carcinoma (RCC) with tubulopapillary growth in the background of tuberculous end-stage kidney disease. Histology of the renal mass consisted of oncocytic cells forming solid, thin tubules and rare papillae. The tumor had abundant eosinophilic oncocytic cells containing occasional cytoplasmic Mallory body–like hyaline globules and a tiny focus of clear cells with intervening mature fat. Both the oncocytic cells and clear cells were immunoreactive for a-methylacyl-CoA racemase, vimentin, pancytokeratin, and CD10, and negative for transcription factor E3, CD15, human melanoma black 45, and c-kit. Mallory body–like hyaline globules were positive for CAM 5.2 and periodic acid–Schiff with or without diastase. Ultrastructurally, the tumor cells had abundant cytoplasmic mitochondria. The present case is a rare case of oncocytic RCC with tubulopapillary growth pattern. The case is unique in that the tumor was mixed with fat component, which is not common in RCC and thus can lead to misdiagnosis.
Granuloma is a chronic inflammatory process associated with non-infectious agents or infectious diseases such as tuberculosis. It is well known that AFB staining, which has been used to determine the etiology of the granulomatous inflammation, lacks both sensitivity and specificity. Due to the slow growth rate of most pathogenic mycobacteria, culturing of organisms can take up to eight weeks. It is not uncommon for specific therapy to be delayed, or for an inappropriate treatment be given to patients without mycobacterial infections or with infections caused by atypical mycobacteria. Determination of the causative agent in Papanicolaou stained cytology specimens gives pathologists even more difficulties when only necrotic material has been aspirated from the center of the granuloma. In recent years, the use of a polymerase chain reaction for the amplification of DNA has appeared promising in terms of speed, efficiency, sensitivity, and specificity.
Since a polymerase chain reaction permits the sensitive genetic analysis of small amounts of tissue, it is ideally suited to the genetic analysis of cytologic specimens. A polymerase chain reaction is easily performed on unfixed and unstained cells, however, an analysis of ethanol fixed and Papanicolaou-stained archival smears has also been described. We have recently established a method to detect Mycobacterium tuberculosis organism by a nested polymerase chain reaction with primers in the insertion sequence IS 6110, using cellular digests of ethanol-fixed and Papanicolaou-stained archival specimens aspirated from the lymph nodes, lungs, thyroid, etc. Inhibitors present in Papanicolaou stained material was removed by destaining the slides with 0.5% HCl solution for 10-30 minutes. Eight out of ten cases which have shown the epithelioid granulomas revealed a positive reaction and four out of ten cases which have shown lymphohistiocytic cells in a necrotic background without any evidence of granuloma revealed a positive reaction. This study showed that it was possible to employ a polymerase chain reaction to detect Mycobacterium tuberculosis in Papanicolaou stained archival cytology specimens.
BACKGROUND TB-PCR is a faster and more sensitive method to detect mycobacterium than acid-fast bacilli (AFB) stain, which is laborious and time consuming. We compared the sensitivity and specificity of AFB stain and TB-PCR and examined the possibility of TB-PCR as a confirmative test without AFB stain in the diagnosis of tuberculosis. METHODS We performed Ziehl-Neelsen stain and nested PCR using a commercially available TB-PCR kit amplifying IS6110 sequence in 81 cases of paraffin-embedded tissues diagnosed as chronic granulomatous inflammation. In addition, we evaluated the morphology of granuloma and the presence of caseation necrosis. RESULTS Of the 81 cases studied, 22 (27.2%) and 40 (49.4%) were positive for AFB stain and TB-PCR, respectively. Of 49 cases accompanying caseation necrosis, 19 (38.8%) were AFB stain positive and 37 (75.5%) were TB-PCR positive; a result that is comparable with that of other reports. Of the 22 AFB-positive cases, 2 were TB-PCR negative. CONCLUSION TB-PCR is very helpful for the diagnosis of tuberculosis in routinely processed, formalin-fixed, paraffin-embedded tissue samples. Nevertheless, AFB stain should continue to be performed at the same time.