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  Anatomic Abstracts

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January 2005

Editors:
Michael Cibull, MD, Professor of Pathology and Laboratory Medicine and Director of Surgical Pathology, University of Kentucky Medical Center, Lexington
Subodh Lele, MD Assistant Professor of Pathology and Laboratory Medicine, University of Kentucky Medical Center
Melissa Kesler, MD, Hematopathology Fellow, University of Texas Southwestern Medical Center at Dallas

Diagnostic application of Epstein-Barr virus-encoded RNA in situ hybridization
Metastatic melanoma in SLNs and nonsentinel lymph node involvement
Prognostic significance of CD20-positive Reed-Sternberg cells in cHD
Role of microwave fixation in microwave-stimulated tissue processing
Seminoma with an exclusive intertubular pattern of growth

Diagnostic application of Epstein-Barr virus-encoded RNA in situ hybridization

Epstein-Barr virus has been implicated in the pathogenesis of nasopharyngeal carcinoma and a range of proliferative lymphoid conditions. In situ hybridization looking for virus-encoded RNA (EBER) transcripts is performed using a commercially available probe. The authors examined how this test is applied in a routine diagnostic setting. They examined 26 cases in which Epstein-Barr virus (EBV) in situ hybridization was requested for diagnostic purposes with regard to its indication for testing, result, and implication for final diagnosis. Cases were classified as possible nasopharyngeal carcinoma, possible EBV-related lymphoma, and possible immunodeficiency-associated lymphoproliferative disorder. Six of nine cases of possible nasopharyngeal carcinoma were EBV in situ hybridization-positive (three of three primary and three of six secondary), confirming the diagnosis. Three of 14 possible lymphoma cases were EBV in situ hybridization-positive, which, along with appropriate ancillary tests, helped in diagnosing Burkitt's lymphoma, lymphomatoid granulomatosis, and extranodal NK/T-cell lymphoma of nasal type. All of the three immunodeficiency-associated cases were EBV in situ hybridization-positive. Two of these were post-transplant lymphoproliferative disorders of monomorphic type. The third case was classified as an HIV-related polymorphic lymphoproliferative disorder. The authors concluded that EBV in situ hybridization is a straightforward and rapid procedure that gives unequivocal results. Used in the appropriate clinicopathological setting, it can be a highly useful ancillary diagnostic aid.

Loughrey M, Trivett M, Lade S, et al. Diagnostic application of Epstein-Barr virus-encoded RNA in situ hybridization. Pathology. 2004;36:301-308.

Reprints: Maurice Loughrey at maurice.loughrey@petermac.org

Metastatic melanoma in SLNs and nonsentinel lymph node involvement

Sentinel node biopsy is widely accepted as the most accurate prognostic indicator of melanoma and is important in managing patients with clinical stage I or II disease. Patients with a positive sentinel node conventionally have undergone completion lymphadenectomy (CLND) of the involved basin, but only 20 percent of patients have involvement beyond the sentinel node, suggesting that CLND may be unnecessary for the other 80 percent of patients. The authors conducted a study to identify criteria that might be used to better identify those persons who should undergo CLND. The authors identified 146 patients who had a positive sentinel node biopsy for malignant melanoma. The subjects' sentinel nodes and lymphadenectomy specimens were re-evaluated pathologically. The metastatic melanoma in each sentinel node was assessed according to its microanatomic location within the node—subcapsular, combined subcapsular and parenchymal, parenchymal, multifocal, or extensive. The location was correlated with the presence of involved nonsentinel nodes in the CLND. The depth of the metastases from the sentinel node capsule was also recorded. The metastatic deposits in the sentinel node were subcapsular in 26 percent of patients. None of these patients had nonsentinel nodes involved on CLND. In the patients whose sentinel node metastases had a different microanatomic location, the rate of nonsentinel node involvement was 22.2 percent overall. The authors concluded that the microanatomic location of metastases within sentinel nodes predicts nonsentinel lymph node involvement. In patients with only subcapsular deposits in the sentinel node, it is possible that CLND could safely be avoided.

Dewar DJ, Newell B, Green MA, et al. The microanatomic location of metastatic melanoma in sentinel lymph nodes predicts nonsentinel lymph node involvement. J Clin Oncol. 2004;22:3345-3349

Reprints: Donald Dewar, Dept. of Histopathology, Royal Surrey County Hospital, Egerton Rd., Guildford, Surrey GU2 7XX, United Kingdom; djdewar@aol.com

Prognostic significance of CD20-positive Reed-Sternberg cells in cHD

In a minority of cases of classical Hodgkin's disease, Reed-Sternberg cells are CD20 positive, but the prognostic significance of CD20 positivity is uncertain. The authors retrospectively reviewed 248 cases of classical Hodgkin's disease (cHD) referred to Memorial Sloan Kettering Cancer Center from May 1992 to November 2000 and immunostained them for CD20. The authors obtained such clinical data as stage and sites of disease, IPI, hematologic parameters, lactate dehydrogenase levels, presence of B symptoms, histologic subtype, patient age, type of treatment, and clinical course. Twenty-eight of the cases (11 percent) were CD20+ . With the exception of hemoglobin level at presentation (which was more often greater than 10.5 g/dL in CD20+ cases), all clinical characteristics were similar for CD20+ and CD20- cases. Median followup was 29.2 months. In multivariate analysis, significant adverse prognostic factors for time to treatment failure included CD20 positivity, elevated white blood cell count, and low absolute lymphocyte count. For overall survival, significant adverse prognostic features were CD20 positivity, elevated WBC, marrow involvement, and age greater than 45 years. Time to treatment failure was significantly shorter for ABVD-treated patients with CD20+cHD compared to CD20- cHD. Among 167 patients treated at Sloan Kettering, both time to treatment failure and overall survival were significantly decreased in CD20+ patients. The authors concluded that CD20 positivity appears to be a poor prognostic factor in cHD, and they expressed the need for routine immunostaining for CD20 as well as a large prospective trial to further evaluate and confirm their findings.

Portlock CS, Donnelly GB, Qin J, et al. Adverse prognostic significance of CD20 positive Reed-Sternberg cells in classical Hodgkin's disease. Br J Haematol. 2004;125: 701-708.

Correspondence: Carol Portlock, Memorial Sloan Kettering Cancer Center, 1275 New York Ave., New York, NY 10021; portlocc@mskcc.org

Role of microwave fixation in microwave-stimulated tissue processing

The authors conducted a study to develop an ultra-rapid, microwave-stimulated histoprocessing protocol that incorporates microwave fixation and produces consistent, high quality sections. A range of fresh autopsy tissues was divided into three groups composed of equal numbers of small and large tissue blocks. The tissues from group one were fixed for eight hours in four percent buffered formaldehyde and processed in a conventional tissue processor for a 15-hour cycle. The tissues from group two were processed in a microwave histoprocessor according to the manufacturer’s recommended protocol of irradiation in a proprietary reagent before being embedded in paraffin. The tissues from group three were processed using the authors’ protocol, which incorporated the addition of microwave fixation in four percent buffered formaldehyde and microwave irradiation in isopropyl alcohol after irradiation in the proprietary reagent. The manufacturer’s protocol resulted in “gray” and “wet look” artifacts in large tissue blocks. These artifacts did not occur in the authors’ protocol, which produced sections that were indistinguishable from those obtained with conventional 23-hour processing. Histochemical and immunohistochemical stains were also indistinguishable, and the tissue blocks cut very smoothly. The authors concluded that incorporating a step to ensure adequate tissue fixation and a step to ensure optimal dehydration and clearing resulted in a microwave histoprocessing protocol that produced consistent results for large and small tissue blocks. Paraffin-impregnated blocks can be produced very rapidly from fresh small and large tissue blocks in 45 and 100 minutes, respectively.

Hafajee ZA, Leong AS. Ultra-rapid microwave-stimulated tissue processing with a modified protocol incorporating microwave fixation. Pathology. 2004;36: 325-329.

Reprint information not available.

Seminoma with an exclusive intertubular pattern of growth

An intertubular pattern of growth may be seen focally in most seminomas, however, an exclusively intertubular pattern is rare and may be missed on initial review. The authors described 12 such cases, none of which presented with a testicular mass. In most of the 12 cases, no mass was evident on gross examination. The exclusive intertubular growth pattern noted varied from conspicuous to subtle. Features noted in areas of intertubular growth in many cases included tubular atrophy with sclerosis and thickening of tubular basement membranes, lymphocytic infiltrates, intratubular germ cell neoplasia of the unclassified type, and Leydig cell hyperplasia. These features may help alert pathologists to the presence of this tumor since the tumor can be clinically occult and not evident on gross inspection. Immunostaining for placental-like alkaline phosphatase and CD-117 is also useful in illustrating the tumor cells and distinguishing them from their mimics. The tumors in two of the 12 cases had metastasized. Therefore, the authors do not recommend using the term “microinvasive” to describe such cases. The authors concluded that a pure intertubular growth pattern in seminoma is rare but should be recognized as a distinctive clinicopathologic subset of seminoma.

Henley JD, Young RH, Wade CL, et al. Seminomas with exclusive intertubular growth: a report of 12 clinically and grossly inconspicuous tumors. Am J Surg Pathol. 2004;28:1163-1168.

Reprints: Dr. John D. Henley, Dept. of Surgical Pathology, University Hospital 3465, 550 N. University Blvd., Indianapolis, IN 46202-5280; jhenley@iupui.edu