Stephen M. Rohan

Patient-Derived Tumor Xenografts Are Susceptible to Formation of Human Lymphocytic Tumors

Patient-derived xenograft (PDX) tumor models have emerged as a new approach to evaluate the effects of cancer drugs on patients’ personalized tumor grafts enabling to select the best treatment for the cancer patient and providing a new tool for oncology drug developers. Here, we report that human tumors engrafted in immunodeficient mice are susceptible to formation of B-and T-cell PDX tumors. We xenografted human primary and metastatic tumor samples into immunodeficient mice and found that a fraction of PDX tumors generated from patients’ samples of breast, colon, pancreatic, bladder and renal cancer were histologically similar to lymphocytic neoplasms. Moreover, we found that the first passage of breast and pancreatic cancer PDX tumors after initial transplantation of the tumor pieces from the same human tumor graft could grow as a lymphocytic tumor in one mouse and as an adenocarcinoma in another mouse. Whereas subcutaneous PDX tumors resembling human adenocarcinoma histology were slow growing and non-metastatic, we found that subcutaneous PDX lymphocytic tumors were fast growing and formed large metastatic lesions in mouse lymph nodes, liver, lungs, and spleen. PDX lymphocytic tumors were comprised of B-cells which were Epstein-Barr virus positive and expressed CD45 and CD20. Because B-cells are typically present in malignant solid tumors, formation of B-cell tumor may evolve in a wide range of PDX tumor models. Although PDX tumor models show great promise in the development of personalized therapy for cancer patients, our results suggest that confidence in any given PDX tumor model requires careful screening of lymphocytic markers.

Differential diagnosis of renal tumors with clear cytoplasm: clinical relevance of renal tumor subclassification in the era of targeted therapies and personalized medicine.

CONTEXT The World Health Organization classification of renal tumors synthesizes morphologic, immunohistochemical, and molecular findings to define more than 40 tumor types. Of these, clear cell (conventional) renal cell carcinoma is the most common malignant tumor in adults and-with the exception of some rare tumors-the most deadly. The diagnosis of clear cell renal cell carcinoma on morphologic grounds alone is generally straightforward, but challenging cases are not infrequent. A misdiagnosis of clear cell renal cell carcinoma has clinical consequences, particularly in the current era of targeted therapies. OBJECTIVE To highlight morphologic mimics of clear cell renal cell carcinoma and provide strategies to help differentiate clear cell renal cell carcinoma from other renal tumors and lesions. The role of the pathologist in guiding treatment for renal malignancies will be emphasized to stress the importance of proper tumor classification in patient management. DATA SOURCES Published literature and personal experience. CONCLUSIONS In challenging cases, submission of additional tissue is often an inexpensive and effective way to facilitate a correct diagnosis. If immunohistochemical stains are to be used, it is best to use a panel of markers, as no one marker is specific for a given renal tumor subtype. Selection of limited markers, based on a specific differential diagnosis, can be as useful as a large panel in reaching a definitive diagnosis. For renal tumors, both the presence and absence of immunoreactivity and the pattern of labeling (membranous, cytoplasmic, diffuse, focal) are important when interpreting the results of immunohistochemical stains.

Primary Adenocarcinoma of the Urinary Bladder: Differential Diagnosis and Clinical Relevance

CONTEXT Glandular lesions of the urinary bladder include a broad spectrum of entities ranging from completely benign glandular lesions to primary and secondary malignancies. Common benign bladder lesions that exhibit glandular differentiation include cystitis cystica, cystitis glandularis, von Brunn nests, nephrogenic adenoma, intestinal metaplasia, urachal remnant, endometriosis, and prostatic-type polyp. The World Health Organization defines primary adenocarcinoma of the bladder as an epithelial malignancy with pure glandular differentiation without evidence of typical urothelial carcinoma. Malignant lesions that should be included in the differential diagnosis of a primary adenocarcinoma of the bladder include noninvasive and invasive urothelial carcinoma with glandular differentiation and secondary malignancies involving the bladder by direct extension or metastasis. The recognition and distinction of these different entities may be a challenge for pathologists, but they are of great clinical importance. OBJECTIVE To review features of primary bladder adenocarcinoma as well as those entities that need to be differentiated from primary bladder adenocarcinoma, with emphasis on clinical findings, pathologic characteristics, and immunoprofiles. DATA SOURCES Selected original articles published in the PubMed service of the US National Library of Medicine. CONCLUSIONS The accurate diagnosis of adenocarcinoma of the urinary bladder is important and challenging. It has to prompt an extensive clinical workup to rule out other glandular lesions in the urinary bladder, especially the possibility of secondary involvement of the bladder by an adenocarcinoma from a different site.

Non-mass-associated intraductal papillomas: is excision necessary? ☆,☆☆

Intraductal papillomas (IDPs) of the breast can be associated with a variety of clinical symptoms and radiologic findings. Surgical excision is often recommended based on the possibility of an associated high-grade lesion. Although the rate of upgrades has been extensively evaluated for IDPs, many studies are hindered by broad inclusion criteria, a lack of pathologic-radiologic concordance, and no standard definition of what constitutes an upgrade. In the current study, we evaluate the risk of upgrade for a specific subset of IDPs: non-mass-associated IDPs. We identified all breast needle core biopsies with a diagnosis of IDP between 2003 and 2010. Patients with associated masses, architectural distortion, or ipsilateral breast cancer were excluded. All needle core biopsy slides and relevant imaging studies were reviewed to ensure pathologic-radiologic concordance. Excision pathology was also reviewed; an upgrade was defined as the presence of ductal carcinoma in situ or invasive carcinoma in the excision. Seventy-nine IDPs that met inclusion criteria were identified and were further divided into 3 histologic categories: micropapilloma, fragmented IDP, and atypical IDP. Micropapillomas and fragmented IDPs had no upgrades (0/37). In patients who did not undergo excision, none subsequently developed ipsilateral breast cancer (follow-up, 50-61 months). This is in contrast to atypical IDPs that had a 33% upgrade rate. One patient with an unexcised atypical IDP developed ipsilateral breast cancer within 2 years. Our data suggest that conservative follow-up is reasonable for non-mass-associated IDPs without atypia regardless of microscopic size, provided that careful pathologic-radiologic correlation is achieved.

The utility of p63, p40, and GATA-binding protein 3 immunohistochemistry in diagnosing micropapillary urothelial carcinoma.

Micropapillary urothelial carcinoma (MPUC) is an uncommon variant of urothelial carcinoma (UC) with an aggressive clinical course. There have been limited studies on the UC markers GATA-binding protein 3 (GATA3), p63, and p40 in MPUC. Our study investigated the immunoreactivity of these 3 markers in MPUC compared with conventional UC of different grades and stages. Immunohistochemistry was performed on 62 cases of high-grade urothelial carcinoma (HGUC), 16 low-grade urothelial carcinoma (LGUC), and 20 MPUC. p63 expression was strong and diffuse in all LGUC, significantly decreased in high stage and HGUC, and virtually absent in MPUC. p40 expression was decreased in HGUC and markedly decreased in MPUC relative to LGUC. These results suggest that loss of p63 expression in a UC appears to be associated with adverse features--including cases with micropapillary differentiation. Decreased GATA3 expression was seen frequently in high-grade and high-pathologic stage (≥pT2) tumors but was retained in MPUC cases. The findings of retained GATA3 expression in MPUC, which often shows a loss of expression of other urothelial markers such as p63, may be helpful for determining the origin of micropapillary carcinoma of unknown primary. Compared with the traditional markers p63 and p40, GATA3 is the most sensitive marker of conventional UC and MPUC.

Urine cytomorphology of micropapillary urothelial carcinoma

Micropapillary urothelial carcinoma (MPUC) is a rare subtype of urothelial carcinoma (UC) with an aggressive clinical course. The cytomorphologic features of MPUC in urine cytology have not been well described. In this study, 23 urine specimens (11 voided urines and 12 bladder washings) from 23 patients with MPUC on follow‐up surgical material and 28 specimens (14voided urines and 14 bladder washings) from 28 patients with high‐grade UCs (HGUC) were retrieved. Cytologic features (nuclear grade, cytoplasmic characteristics), architectural features (single cell pattern, true papillary structures, flat sheets/nests, three dimensional clusters, micropapillary (inside‐out, acinar‐like, or cauliflower with nuclei located peripherally)), and necrosis were evaluated. Clinical follow‐up was obtained by chart review. Two findings, micropapillae and cytoplasmic vacuoles, were seen more frequently in MPUC compared to HGUC, 81.0% vs. 14.3%, and 57.1% vs. 14.3%, respectively. The combination of these two findings had a sensitivity of 78%, a specificity of 86%, a positive predictive value of 82%, and a negative predictive value of 83% for the diagnosis of MPUC on subsequent biopsy. MPUC and HGUC can both exhibit a single cell pattern, papillary structures, flat sheets/nests, three dimensional clusters, high‐nuclear grade, and necrosis, thus these findings are not useful in distinguishing these entities. Chart review revealed that patients with MPUC had a higher rate of metastasis to lymph nodes and distant organs than HGUC, 57% vs. 4%. Therefore, the findings of cytoplasmic vacuoles and micropapillary structures in UC from a urine cytology specimen are associated with MPUC on subsequent biopsy. Diagn. Cytopathol. 2013.

Xp11.2 translocation renal cell carcinoma with PSF-TFE3 rearrangement.

Xp11.2 translocation renal cell carcinoma (Xp11.2 RCC) is a subtype of RCC characterized by translocations involving a breakpoint at the TFE3 gene (Xp11.2). Moderate to strong nuclear TFE3 immunoreactivity has been recognized as a specific diagnostic marker for this type of tumor. However, exclusive cytoplasmic localization of a TFE3 fusion protein was reported in UOK 145 cells, a cell line derived from an Xp11.2 RCC harboring the PSF-TFE3 translocation. If reproducible using immunohistochemistry (IHC), this finding would have important implications for pathologists in the diagnosis of Xp11.2 RCC, calling into question the specificity of nuclear immunoreactivity for TFE3 in these tumors. The purpose of this study was to determine whether the above-noted cytoplasmic localization of the TFE3 fusion protein could be reproduced using IHC. UOK 145 cells and fresh frozen tissue from 2 clinical cases of Xp11.2 RCC found to harbor the PSF-TFE3 gene rearrangement (by cytogenetic testing) were collected. All samples were subjected to histopathologic evaluation by board-certified pathologists, TFE3 IHC, reverse transcription polymerase chain reaction, and Sanger sequencing analysis. A strong nuclear TFE3 immunoreactivity was demonstrated in all samples including the UOK 145 cell line. No cytoplasmic immunoreactivity was seen. Reverse transcription polymerase chain reaction and Sanger sequencing confirmed the previously reported PSF-TFE3 gene fusion between exon 9 of PSF and exon 6 of TFE3 in the UOK 145 cell line and in one of 2 clinical cases of Xp11.2 RCC. A novel PSF-TFE3 gene fusion between exon 9 of PSF and exon 5 of TFE3 was detected in the second clinical case of Xp11.2 RCC.

Immunoexpression of napsin a in renal neoplasms

BackgroundImmunohistochemistry (IHC) for napsin A has been widely used to support a diagnosis of lung adenocarcinoma with high sensitivity. In this study, we evaluated immunoreactivity for napsin A in a broad spectrum of renal neoplasms by using tissue microarrays (TMA).MethodsDuplicate TMA of 159 surgically excised renal neoplasms of various types were constructed. IHC for napsin A was performed on TMAs with appropriate positive and negative controls.ResultsNapsin A was expressed in Acquired cystic disease associated renal cell carcinoma (RCC) (2/2, 100.0%), chromophobe RCC (5/45, 11.1%), clear cell RCC (10/23, 43.5%), clear cell papillary RCC (9/19, 47.4%), metanephric adenoma (3/3, 100.0%), oncocytoma (13/23, 56.5%), and papillary RCC (31/37, 83.8%). Expression of napsin A was not seen in mucinous tubular and spindle cell carcinoma (0/1, 0.0%), TFE/MITF RCC 0/1, 0.0%), and urothelial carcinoma (0/6, 0.0%).ConclusionsNapsin A is expressed in both common and rare sub-types of renal neoplasms with variable sensitivity. Based on our results, napsin A is not specific for lung adenocarcinoma. When a metastatic carcinoma of unknown primary is positive for napsin A, the differential diagnosis should include tumors of both renal and lung origin.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9558727831304717.

Metastatic chromophobe renal cell carcinoma in pleural fluid cytology: review of literature and report of a case.

The majority of chromophobe renal cell carcinomas (CHRCC) are not aggressive, however, a subset are. The potential for metastasis makes recognition of CHRCC cells in cytologic preparations important for patient surveillance, management, and treatment. We report the detection of an aggressive form of CHRCC in pleural fluid cytology with histopathologic confirmation on subsequent pleural biopsy. Sarcomatoid portions of the original CHRCC, and the pleural metastasis, demonstrated loss of diffuse membranous staining with C‐KIT. Diagn. Cytopathol. 2012.

Diagnostic accuracy of frozen-section analysis of cancer-containing bladder transurethral resection specimens for the presence of muscularis propria invasion

Aims Frozen section (FS) consultation is generally an accurate diagnostic modality. At our institution, we are frequently asked to assess transurethral resection specimens (TURBT) at FS for muscularis propria (MP) invasion by carcinoma. This study documents our experience in evaluating cancer-containing TURBT specimens at FS for MP invasion. Methods 32 TURBT sent for FS from 2008–2010 were identified. The FS and permanent section (PS) diagnoses were reviewed. Cases excluded from the calculation of test performance included: (1) cases without cancer on FS or PS slides, (2) FS diagnosis deferred, (3) cases without MP on FS and subsequent PS slides. Sensitivity (SEN), specificity (SPEC), positive predictive value (PPV), and negative predictive value (NPV) for identifying MP invasion at FS were calculated. Results In 6 cases, no cancer was present in FS or PS slides (18%). The FS diagnosis was deferred on 3 cases (9%). In one case (3%) MP was not present in the FS or the subsequent PS slides. Of the remaining 22 cases, 2 false positive and 6 false negative diagnoses of MP invasion were identified. The test performance for FS assessment of MP invasion in TURB were SEN=33%, SPEC=84%, PPV=60%, and NPV=64%. Conclusions Identifying MP invasion on PS can be difficult, and our results suggest that this is more difficult at FS. Though this study is based on small numbers, our results point to the conclusion that examination of TURBT specimens for MP invasion is best done on PS.