Differentiation of Renal Tubular Epithelium in Renal Transplantation Cytology

Transcription

1 Differentiation of Renal Tubular Epithelium in Renal Transplantation Cytology G. BERRY SCHUMANN, M.D., LAWRENCE J. PALMIERI, B.S., C.T.(ASCP), AND DAVID B. JONES, M.D. Schumann, G. Berry, Palmieri, Lawrence J., and Jones, David B.: Differentiation of renal tubular epithelium in renal transplantation cytology. Am J Clin Pathol 67: , Increased numbers of renal tubular epithelial cells are present in the urinary sediments of renal transplant recipients during acute rejection. Few investigators have described characteristics of renal tubular epithelial cells in cytologic preparations. This study compiles morphologic characteristics of various tubular epithelial cells and determines the type of the present during acute allograft rejection. The results demonstrate that cuboidal forms from the small collecting ducts are the predominent tubular epithelial cells exfoliated in voided urine during acute allograft rejection. (Key words: Renal tubular epithelial cells; Acute renal allograft rejection; Urine cytology.) URINARY CYTOLOGY has been proposed as a method for early diagnosis of acute renal allograft rejection. 2,5,6,8,9 The authors observed renal tubular epithelial cells, and occasionally lymphocytes, in increased numbers as part of a cellular pattern demonstrating the early onset of acute renal allograft rejection. However, problems may occur in distinguishing renal tubular epithelial cells from immature lymphocytes, histiocytes and transitional epithelial cells in urinary cytology. This study compiles morphologic characteristics of renal tubular epithelial cells and determines the origin of those commonly found in urine during acute renal allograft rejection. Materials and Method Histologic sections and tissue imprints of kidneys from patients without significant renal disease were obtained from both surgical and autopsy specimens and stained with hematoxylin and eosin and periodic acid-schiff (PAS). Tissue imprints were obtained by slicing a fresh unfixed kidney transversely through the Received May 17, 1976; accepted for publication May 28, Address reprint requests to Dr. Schumann: Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, Ohio Department of Pathology, Upstate Medical Center, State University of New York, Syracuse, New York cortex, medulla, and pelvis. These imprints were stained with hematoxylin and eosin and by the Papanicolaou method. Also, urinary sediments from 30 renal transplant recipients during acute allograft rejection were examined. Results Histologic Examination (Figs. I-A, 2-A, and 3-A) To determine the general characteristics of renal tubular epithelial cells in urine, the authors reviewed authoritative sources describing the histology of the nephron 1 ' 3,4,7 and compared their descriptions with hematoxylin and eosin- and PAS-stained tissue sections of non-rejecting kidneys (Table 1). From this investigation, three cell types cuboidal, columnar, and flat were consistently observed in the epithelium of the and collecting ducts. Proximal convoluted renal could not be classified in the above types, because of their marked variation in size and shape. Tissue Imprints "Mechanical Exfoliation" (Figs. 1 B and C,2 B and C, and 3 B and C) The authors investigated morphologic changes that occurred in the renal tubular epithelial cells when placed outside their histologic setting. Recognition of these changes aids in the identification of cells with "true" exfoliation. Renal from the proximal convoluted tubule (type I), distal convoluted tubule (type II), small collecting duct (type III), and large collecting duct (type IV) were all readily identifiable, and confirmed the results of studies of the histologic sections (Table 2). Frequently, tissue imprints from the renal medulla showed long tubular

2 Vol. 67 No. 6 RENAL TUBULAR EPITHELIUM 581 FIG. I. A, normal histologic section from the renal cortex, showing many proximal convoluted renal tubular cells. Note the faint brush border (arrows). Hematoxylin and eosin. x430. B, binucleated proximal convoluted tubule cell obtained from a tissue imprint of the renal cortex. Papanicolaou stain. x430. C, two proximal convoluted tubule cells with eccentric nuclei, irregular shapes, and abundant granular cytoplasm. These cells were not identified during acute renal rejection. Papanicolaou stain. x430. fragments (Fig. 4, A and B) and contained flattened transitional cells (type V). Urinary Cytology ''True" Exfoliation Examination of several urinary sediments obtained from renal transplant recipients during acute allograft rejection again revealed cuboidal, columnar and flat types of renal. Cuboidal forms approximately ju,m in diameter predominated during acute rejection. This cuboidal cell (type III) correlates with the cells lining the small collecting duct that we observed histologically. These cells exfoliated in increased numbers during acute rejection episodes and diminished in number after anti-rejection therapy. Despite slight to moderate degeneration, many renal retained their characteristic cuboidal shape when found singly, in casts, and also as tissue fragments. Columnar (type IV) and flat (type V) renal tubular cells were also seen, but these cells could not be consistently correlated with acute rejection episodes. However, these forms were frequently seen in the urinary sediment from transplant recipients during renal infarction. Most importantly, from the proximal and distal convoluted of the nephron could not be confidently recognized during acute rejection. Several specimens of urine had cells with eosinophilic granular cytoplasm and small pyknotic nuclei, but their origin was undetermined. Discussion General agreement exists regarding the morphologic characteristics of lymphocytes, histiocytes, and transitional cells, all of which are commonly seen in renal transplant cytology. However, renal tubular epithelial cells in urine have been described quite differently by various investigators. For example, Taft and associates 9 describe the diameter of the cells as /xm, and report finding of single bizarre cells as much as 70 /u.m in diameter. Kline and co-workers 6 suggest that cells exfoliated from renal during rejection are 7 to 9 fim in size with hyperchromatic nuclei and scant cytoplasm. At the same time, one reference 3 describes the size of renal as less than 15 fim. In short, descriptions of renal tubular cells are few, and there are significant variations in them. From this study we conclude that the "typical" renal tubular epithelial cells (type III) seen during acute renal allograft rejection are cuboidal, measuring approxi-

3 582 SCHUMANN, PALMIERI AND JONES A.J.C.P.. J u n e 1977 FIG. 2. A, histologic section from the normal renal cortex, showing both distal convoluted cells (large arrows) and small collecting duct cells (small arrows). Hematoxylin and eosin. x430. B, distal convoluted tubule cell obtained from a tissue imprint of the renal cortex. Papanicolaou stain. x430. C, several cuboidal cells from the small collecting duct. Although these cells were obtained from a tissue imprint, they correlate with the predominant exfoliated renal tubule cell during acute allograft rejection. Papanicolaou stain. x430. f <A B FIG. 3. A, histologic section from the normal renal medulla, showing the large collecting duct cells (large arrow). A few flat cells from the thin loop of the nephron are also present (small arrow). Hematoxylin and eosin. x430. B, row of large collecting duct cells obtained from a tissue imprint of the renal medulla. Similar cells are seen in urinary cytology of renal allograft recipients during acute rejection. Papanicolaou stain. x430.

4 Vol. 67 No. 6 RENAL TUBULAR EPITHELIUM 583 Table I. Characteristics of Renal Tubular Epithelial Cells Obtained from Histologic Sections of Normal Kidney (Hematoxylin-Eosin and PAS Stains) Origin Described in Literature 1,3,4,7 Our Observations I. Examined in the cortical portion of histologic section A. Proximal convoluted Coarsely granular eosinophilic cytoplasm. Nucleus placed near basement membrane. Distal convoluted C. Small collecting Coarsely granular eosinophilic cytoplasm. Nucleus placed near basement membrane. No brush order. Light or dark staining cytoplasm. Centrally placed nucleus. II. Examined in the medullary portion of histologic section A. Thin segment of loop Light staining cytoplasm, of Henle Flattened nucleus. B. Regenerating C. Large collecting Not described. Light or dark staining. Coarsely granular eosinophilic cytoplasm. Indistinct cell borders. Round uniform nucleus with a prominent nucleolus. Nucleus placed near basement membrane. Brush border seen occasionally /xm in height with undetermined width. Least number of nuclei/tubule. Coarsely granular eosinophilic cytoplasm. Distinct cell borders. Uniform round nucleus with less prominent nucleoli. Central position nucleus or toward basement membrane. ~10 x 10 /xm. Light staining cytoplasm, occasional perinuclear clearing (artifact). Distinct cell borders. Round to slightly irregular, centrally placed nucleus. No prominent nucleoli. ~I0 x 14 /xm. Light staining cytoplasm. Indistinct cell borders. Oval to spindle-shaped nucleus /xm in length. Light staining cytoplasm. Indistinct cell borders. Round, oval or spindle-shaped nucleus with prominent nucleoli. Variable size. Light staining cytoplasm with fine granules. Distinct cell borders. Round or irregular nucleus without prominent nucleoli. Perinuclear clearing. Centrally placed nucleus or toward basement membrane /xm in height and 7-10 /xm in width. Table 2. Characteristics of Renal Tubular Epithelial Cells Obtained from Tissue Imprints of Normal Kidney (Hematoxylin-Eosin and Papanicolaou Stains) Cell Type Area of Imprint* Characteristics Cell Identification 1. Type I Cortex Several large cells measuring ~20-60 /xm. Abundant coarsely granular eosinophilic cytoplasm. Indistinct cell borders. Round eccentric nucleus with occasional prominent nucleolus. Brush borders not apparent. Occasional binucleated forms. Proximal convoluted 2. Type II Medulla and cortex Few cuboidal cells measuring 14 x 14 /xm. Granular eosinophilic cytoplasm. Distinct cell borders. Round centrally placed nucleus. Distal convoluted 3. Type III Cortex and medulla Several cuboidal cells measuring ~12 x 18 /xm. Light staining eosinophilic cytoplasm. Distinct cell borders. Round centrally placed nucleus. Small collecting 4. Type IV Medulla Occasional columnar cell measuring ~ 10 x 20 /xm. Light staining cytoplasm. Slightly eccentric nucleus. Occurring in small "castlike" tissue fragments. Large collecting 5. Type V Medulla and Pelvis Several epithelial cells measuring ~20-30 x /xm. Oval to spindle-shaped nucleus. Abundant elongated light staining cytoplasm with irregular cell borders. Few tissue fragments with overlapping nuclei. Transitional cells (urothelium)

5 584 SCHUMANN, PALMIERI AND JONES A.J.C.P. June % m v v> $ * FIG. 4. A, large intact tissue fragment of a nephron obtained from a tissue imprint of the renal medulla. Several intact "cylinders" or tissue fragments of flat renal tubule cells have been seen in urinary cytologic examinations, especially during renal infarction. Papanicolaou stain. x430. B, tissue imprint, showing a fragment containing flat renal tubule epithelial cells. Although in urinary cytology the cells are considered transitional epithelium (urothelium), when surrounding urinary casts in a cylindrous fragment, they suggest a renal tubular origin. Papanicolaou stain. x430. «-. B mately /j,m, with slightly hyperchromatic nuclei and nongranular cytoplasm, and originate in the small collecting ducts. Cells from the thin loop of Henle, regenerating cells, and columnar cells from the large collecting duct are also seen, but are less predictable in diagnosing acute rejection. Cells from the proximal or distal convoluted were not recognizable. Although PAS staining for the brush border of proximal renal was readily identifiable on histologic section and tissue imprints, brush borders could not be identified in urinary cytology. Cells from both of these regions contain many mitochondria and lysozymes, which probably accentuates their degeneration upon exfoliation. Thus, it is clear from this study that when the urinary tract is not obstructed, exfoliative cytology from specimens of urine can provide an important clue regarding renal parenchymal involvement during acute rejection. Currently, we are pursuing cytochemical technics to improve our accuracy in recognizing renal. References 1. Bloom W, Fawett DW: A Textbook of Histology. Ninth edition. Philadelphia, W. B. Saunders, Bossen EH, Johnston WW, Amatulli J, et al: Exfoliative cytopathologic studies in organ transplantation. III. The cytologic profile or urine during acute renal allograft rejection. Acta Cytol 14: , Greep RO, Weiss L: Histology. Third edition. New York, McGraw-Hill, Heptinstall RH: Pathology of the Kidney, Boston, Little, Brown, Kauffman HM Jr, Clark RF, Magee JH, et al: Lymphocytes in urine as an aid in the early detection of renal homograft rejection. Surg Gynecol Obstet 119:25-36, Kline TS, Craighead JE: Renal homotransplantation. The Cytology of the Urine Sediment. Am J Clin Pathol 47: , Strauss MB, Welt LO: Diseases of the Kidney. Second edition. Boston, Little, Brown, Schumann GB, Burleson RL, Henry JB, et al: Urinary cytodiagnosis of acute renal allograft rejection using the cytocentrifuge. Am J Clin Pathol 67: , Taft PD, Flax MH: Urinary cytology in renal transplantation: Association of renal and graft rejection. Transplantation 4: , 1966