Olaf Kaufmann

Value of p63 and Cytokeratin 5/6 as Immunohistochemical Markers for the Differential Diagnosis of Poorly Differentiated and Undifferentiated Carcinomas

To facilitate the differential diagnosis of poorly differentiated metastatic carcinomas of unknown primary site, we evaluated p63 and cytokeratin (CK) 5/6 as immunohistochemical markers for squamous cell carcinomas. The study cases were as follows: squamous cell carcinoma of the lungs, head/neck, esophagus, cervix uteri, or anal canal, 73; non-squamous cell carcinomas of various primary sites, 141; and urothelial carcinoma, 20. We also tested 14 malignant mesotheliomas. Immunoreactivity for p63 was as follows: squamous cell carcinomas, 59 (81%); urothelial carcinoma, 14 (70%), most often with diffuse staining patterns; non-squamous cell carcinomas, 20 (14.2%), resulting in a specificity of 0.86 of p63 for squamous cell carcinomas. Coexpression of p63 and CK5/6 had a sensitivity of 0.77 and a specificity of 0.96 for squamous cell carcinomas. Increasing the minimal criterion of positive immunostaining for both markers to more than 50% of immunoreactive tumor cells resulted in a specificity of 0.99, although the sensitivity diminished to 0.66. All malignant mesotheliomas were negative for p63. Our data suggest that positive immunostaining for both p63 and CK5/6 in poorly differentiated metastatic carcinomas is highly predictive of a primary tumor of squamous epithelial origin.

Uroplakin III is a highly specific and moderately sensitive immunohistochemical marker for primary and metastatic urothelial carcinomas.

Uroplakins are specific differentiation products of terminally differentiated superficial urothelial cells. We tested the value of a new commercially available monoclonal antibody against uroplakin III (clone AU 1) as a paraffin-reactive immunohistochemical marker for primary and metastatic urothelial carcinomas. The study cases included 67 urothelial carcinomas of the urinary tract (35 primary tumors, 32 metastases) and 318 nonurothelial carcinomas, as well as 5 benign Brenner tumors and 2 transitional cell carcinomas of the ovaries. Uroplakin III was detected in 21 (60%) of the primary urothelial carcinomas and 17 (53%) of the metastases, resulting in an overall sensitivity of 0.57. The studied Brenner tumors also were immunoreactive for uroplakin III. All other studied carcinomas were consistently uroplakin III-negative (specificity 1.00). We found the new monoclonal antibody AU 1 against uroplakin III to be a highly specific paraffin-reactive immunohistochemical marker for urothelial tumors with a moderate sensitivity for the identification of primary and metastatic urothelial carcinomas.

Comparison of Immunoglobulin Heavy Chain Rearrangements Between Peripheral and Glandular B Cells in a Patient with Primary Sjögren's Syndrome

Myoepithelial sialadenitis (MESA) of the major salivary glands is a characteristic feature of primary Sjögrens syndrome (pSS). To delineate systemic and organ‐specific influences on B cells in a patient with pSS and benign MESA, individual B cells were simultaneously obtained from the peripheral blood and inflamed parotid gland. Immunoglobulin variable heavy chain (VH) rearrangements in single sorted CD19+ B cells were subsequently amplified, sequenced and analysed. Despite the presence of two clonal expansions using VH1‐08 and VH2‐70 segments, respectively, the majority of glandular B cells were polyclonal, resembling the VH gene usage and mutational pattern of the corresponding blood population. However, striking differences were observed in the proportion of cells expressing mutated VH rearrangements (blood, 28.9% versus parotid, 80.4%; P < 0.0001). Moreover, the glandular productive VH rearrangements differed significantly from their blood counterparts by a higher mutational frequency (P < 0.0001), shorter CDR3 lengths (P = 0.001) and a less frequent usage of JH6 (P = 0.0292), indicating an accumulation of memory B cells in the inflamed parotid. Thus, both preferential influx/homing of memory B cells and local proliferation may contribute to the pattern of benign MESA in pSS. Notably, one of the glandular clonal rearrangements (using VH1‐08) was also detected in the patients peripheral repertoire.

Subcutaneous Crystal-Storing Histiocytosis Associated with Lymphoplasmacytic Lymphoma (Immunocytoma)

A case of massive crystal-storing histiocytosis with extensive involvement of the subcutaneous adipose tissue in a 61-year-old caucasian woman with a lymphoplasmacytic lymphoma (immunocytoma) in transformation to a large cell lymphoma is presented. Paraffin-section immunohistochemistry demonstrated a monoclonal IgM/ kappa immunphenotype of the lymphoma cells and revealed IgM/kappa and, to a lesser extent, IgG/lambda in the crystal-containing histiocytes. Ultrastructurally, the electron dense intracytoplasmic crystals had variables shapes, were occasionally membrane-bound and measured up to 6 microns. The finding are briefly discussed.

Analysis of immunoglobulin light chain rearrangements in the salivary gland and blood of a patient with Sjögren's syndrome.

Patients with Sjögrens syndrome (SS) have characteristic lymphocytic infiltrates of the salivary glands. To determine whether the B cells accumulating in the salivary glands of SS patients represent a distinct population and to delineate their potential immunopathologic impact, individual B cells obtained from the parotid gland and from the peripheral blood were analyzed for immunglobulin light chain gene rearrangements by PCR amplification of genomic DNA. The productive immunglobulin light chain repertoire in the parotid gland of the SS patient was found to be restricted, showing a preferential usage of particular variable lambda chain genes (Vλ2E) and variable kappa chain genes (VκA27). Moreover, clonally related VL chain rearrangements were identified; namely, VκA27–Jκ5 and VκA19–Jκ2 in the parotid gland, and Vλ1C–Jλ3 in the parotid gland and the peripheral blood. Vκ and Vλ rearrangements from the parotid gland exhibited a significantly elevated mutational frequency compared with those from the peripheral blood (P < 0.001). Mutational analysis revealed a pattern of somatic hypermutation similar to that found in normal donors, and a comparable impact of selection of mutated rearrangements in both the peripheral blood and the parotid gland. These data indicate that there is biased usage of VL chain genes caused by selection and clonal expansion of B cells expressing particular VL genes. In addition, the data document an accumulation of B cells bearing mutated VL gene rearrangements within the parotid gland of the SS patient. These results suggest a role of antigen-activated and selected B cells in the local autoimmune process in SS.

Specificity of PCR-based clonality analysis of immunoglobulin heavy chain gene rearrangements for the detection of bone marrow involvement by low-grade B-cell lymphomas.

A study was performed to investigate the utility of polymerase chain reaction (PCR)‐based analysis of immunoglobulin heavy chain (IgH) gene rearrangements for the diagnosis of low‐grade malignant B‐cell lymphomas on formalin‐fixed, EDTA‐decalcified, and paraffin‐embedded bone marrow trephine biopsies. On amplifying two DNA samples per biopsy, no reproducible monoclonal PCR result was found in 32 patients with reactive lymphoid hyperplasias. In contrast, 5/14 patients with known low‐grade B‐cell lymphomas, but histomorphologically and immunohistochemically lymphoma‐free bone marrow, showed a reproducible monoclonal IgH gene rearrangement. In three of these cases, sequence analysis revealed completely different amplification products on comparing bone marrow and lymph node infiltrations, while in the other two cases the products were identical. In one of the latter biopsies, an unequivocal lymphoma infiltrate was found after step sectioning of the biopsy, while the other case remained lymphoma‐free according to conventional criteria. A third group of three patients with known lymphomas and bone marrow findings that were suggestive but not diagnostic of bone marrow involvement showed monoclonal PCR results in all three cases, with identical sequences in bone marrow and extramedullary lymphoma infiltrates. These data suggest that a reproducible monoclonal IgH gene rearrangement is highly specific for the presence of malignant B‐cells in bone marrow. In staging procedures for low‐grade B‐cell lymphomas, PCR yields no additional information in cases that are morphologically and immunohistochemically lymphoma‐free after evaluation of representative sections. PCR may be useful in equivocal cases, provided that IgH gene rearrangements of extramedullary lymphoma and bone marrow are sequenced and compared. Copyright