Intraductal Carcinoma of the Prostate versus Simulants: A Differential Diagnosis Growing in Clinical Impact.

Despite its first recognition even longer ago, in the past nearly 20 years, intraductal carcinoma of the prostate has become a standard histopathologic reporting parameter conveying a strong negative prognostic factor for prostatic adenocarcinoma. When seen at biopsy, intraductal carcinoma of the prostate is associated with risk for aggressive prostatectomy outcomes, including frequently high-grade, high-stage, high-volume disease, with increased risk for recurrence and progression. Multiple organizations, including the uropathology subspecialty societies to the World Health Organization, recognize and recommend reporting the presence of intraductal carcinoma, whether sampled in "pure" form or present with concomitant invasive adenocarcinoma. Moreover, emerging scholarship relates intraductal carcinoma to higher prevalence of homologous recombination repair deficiency mutations in prostatic adenocarcinoma, whether somatic or germline, which serve as indications for approved targeted therapies. Taken together, this is a diagnosis for the histopathologist not to miss. In view of these elevated stakes and the opportunity to further precision medicine, this review details neoplastic and non-neoplastic simulants in the differential diagnosis of intraductal carcinoma of the prostate.

Contemporary Diagnostic Reporting for Prostatic Adenocarcinoma: Morphologic Aspects, Molecular Correlates, and Management Perspectives.

The diagnosis and reporting of prostatic adenocarcinoma have evolved from the classic framework promulgated by Dr Donald Gleason in the 1960s into a complex and nuanced system of grading and reporting that nonetheless retains the essence of his remarkable observations. The criteria for the "Gleason patterns" originally proposed have been continually refined by consensuses in the field, and Gleason scores have been stratified into a patient-friendly set of prognostically validated and widely adopted Grade Groups. One product of this successful grading approach has been the opportunity for pathologists to report diagnoses that signal carefully personalized management, placing the surgical pathologist's interpretation at the center of patient care. At one end of the continuum of disease aggressiveness, personalized diagnostic care means to sub-stratify patients with more indolent disease for active surveillance, while at the other end of the continuum, reporting histologic markers signaling aggression allows sub-stratification of clinically significant disease. Whether contemporary reporting parameters represent deeper nuances of more established ones (eg, new criteria and/or quantitation of Gleason patterns 4 and 5) or represent additional features reported alongside grade (intraductal carcinoma, cribriform patterns of carcinoma), assessment and grading have become more complex and demanding. Herein, we explore these newer reporting parameters, highlighting the state of knowledge regarding morphologic, molecular, and management aspects. Emphasis is made on the increasing value and stakes of histopathologists' interpretations and reporting into current clinical risk stratification and treatment guidelines.

The New WHO Category of "Molecularly Defined Renal Carcinomas": Clinical and Diagnostic Features and Management Implications.

The evolution of classification of renal tumors has been impacted since the turn of the millennium by rapid progress in histopathology, immunohistochemistry, and molecular genetics. Together, these features have enabled firm recognition of specific, classic types of renal cell carcinomas, such as clear cell renal cell carcinoma, that in current practice trigger histologic-type specific management and treatment protocols. Now, the fifth Edition World Health Classification's new category of "Molecularly defined renal carcinomas" changes the paradigm, defining a total of seven entities based specifically on their fundamental molecular underpinnings. These tumors, which include TFE3-rearranged, TFEB-altered, ELOC-mutated, fumarate hydratase-deficient, succinate dehydrogenase-deficient, ALK-rearranged, and SMARCB1-deficient renal medullary carcinoma, encompass a wide clinical and histopathologic phenotypic spectrum of tumors. Already, important management aspects are apparent for several of these entities, while emerging therapeutic angles are coming into view. A brief, clinically-oriented introduction of the entities in this new category, focusing on relevant diagnostic, molecular, and management aspects, is the subject of this review.

A TFEB-Amplified Renal Cell Carcinoma with Long-Term, Complete Immunotherapy Response: Retrospective Support for the Value of Molecular Classification.

Recent years have seen the recognition and establishment of numerous subtypes of renal cell carcinoma (RCC), including adoption of an entire category of "molecularly defined renal carcinomas" in the fifth Edition of World Health Organization Classification. To add value, new diagnostic entities should be clinicopathologically distinct, or better, imply specific management and treatment angles, especially if adjunctive testing is needed for diagnosis. One such promising future treatment angle for a molecularly defined subtype, TFEB-amplified RCC, is immunotherapy, for which recent scholarship has demonstrated frequent expression of PD-L1. Herein, we report a case of metastatic TFEB-amplified RCC, where the patient experienced a long-term, complete response to PDL1-directed therapy, which had been serendipitously used years ago under a renal tumor subtype-agnostic indication. This promising experience suggests formal exploration of immunotherapy for these tumors.

Unexpected Clinical Outcome for Myxoinflammatory Fibroblastic Sarcoma, When Should They Be Considered High Grade?

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare tumor of soft tissue. It typically presents as a low-grade sarcoma with myxoid stroma, has a predilection for distal extremities, and displays a high propensity for local recurrence, but low metastatic potential. The risk factors associated with high-risk lesions metastasizing are poorly defined. In cases where the tumor metastasizes, therapeutic options are few, and death is rare. Our case discusses an aggressive MIFS that progressed from a painless lesion on a patient's calf, to her death from a malignant pleural effusion within 21 months. The 58-year-old woman presented with a mass on her left calf. It was excised and was originally thought to be a benign process. It re-grew quickly after the initial resection, and she underwent re-excision of the mass. The pathologic examination was consistent with an MIFS. Despite negative margins on her second resection and an attempt at local control with radiotherapy, it metastasized to her lungs within less than 2 years. This resulted in a malignant pleural effusion that caused her death. An MIFS is typically benign but can metastasize in atypical cases. Even if the disease is metastatic, it is unlikely to be the cause of death. Treatment of metastatic MIFS is poorly defined, but there are suggested therapies beyond surgical resection and radiotherapy. Successful treatment of an MIFS should include a high index of suspicion in extremity lesions, screening for metastasis, and possible targeted therapies based on tumor genomics.

Antagonism between Prdm16 and Smad4 specifies the trajectory and progression of pancreatic cancer.

The transcription factor Prdm16 functions as a potent suppressor of transforming growth factor-beta (TGF-ß) signaling, whose inactivation is deemed essential to the progression of pancreatic ductal adenocarcinoma (PDAC). Using the KrasG12D-based mouse model of human PDAC, we surprisingly found that ablating Prdm16 did not block but instead accelerated PDAC formation and progression, suggesting that Prdm16 might function as a tumor suppressor in this malignancy. Subsequent genetic experiments showed that ablating Prdm16 along with Smad4 resulted in a shift from a well-differentiated and confined neoplasm to a highly aggressive and metastatic disease, which was associated with a striking deviation in the trajectory of the premalignant lesions. Mechanistically, we found that Smad4 interacted with and recruited Prdm16 to repress its own expression, therefore pinpointing a model in which Prdm16 functions downstream of Smad4 to constrain the PDAC malignant phenotype. Collectively, these findings unveil an unprecedented antagonistic interaction between the tumor suppressors Smad4 and Prdm16 that functions to restrict PDAC progression and metastasis.

Universal Mismatch Repair Protein Screening in Upper Tract Urothelial Carcinoma.

OBJECTIVES: Universal screening of upper tract urothelial carcinoma (UTUC) for Lynch syndrome by mismatch repair (MMR) protein immunohistochemistry (IHC) has been recommended by some investigators. Herein, we assess this recommendation retrospectively by simulating its performance on a retrospective, unselected cohort of UTUCs, with comparison to the established setting of colorectal and endometrial adenocarcinoma. METHODS: We assessed for complete loss of MMR protein (MLH1, MSH2, MSH6, and PMS2) IHC in 74 consecutive cases of UTUC and then tabulated clinical and pathologic factors. MMR findings from same-institution colorectal and endometrial adenocarcinomas were tabulated for comparison. RESULTS: We observed loss of at least one MMR protein in 12% in our UTUC cohort (three MSH2/MSH6, three MSH6 only, one MLH1/PMS2, and two PMS2 only). Of these nine cases (seven males, two females, median age 67 years, five associated with colorectal adenocarcinoma), at least three (4% of the overall cohort) proved to be Lynch syndrome. Overall, MMR loss in UTUC was comparable to colorectal (11%; 50 of 471 cases) and endometrial (12%; 12 of 101 cases) adenocarcinomas. CONCLUSIONS: The rate of MMR loss observed in UTUC was comparable to that in the established setting of colorectal and endometrial adenocarcinomas, supporting universal UTUC screening at our institution and others.

Peyronie disease: a clinicopathologic study of 71 cases with emphasis on histopathologic patterns and prevalent metaplastic ossification.

Peyronie disease (PD) is a benign, superficial fibromatosis involving the fascial structures of the penis, causing deformity, pain, and loss of function, for which there are few contemporary studies of the histopathology. We performed a multi-institutional review of 74 routine and consultation specimens submitted with clinical concern for PD. Of these, three non-PD lesions were identified and excluded (a myointimoma, a mammary-type myofibroblastoma, and fibrocalcific atherosclerosis). Of the 71 confirmed to be PD, the majority of patients were white (83%), with a median age of 55 years (range: 26-88). The dorsal aspect of the penis was the most common site involved (78%), followed by lateral (12%) and ventral (10%) aspects. The median degree of curvature was 70° (range: 20-360°). On review, three overall histologic patterns characterized the lesions resected: dense fibrotic plaque (61%), dense fibrotic plaque with focal or patchy metaplastic ossification (35%), and plaque composed predominantly of metaplastic ossification (4%). The fibrotic component was predominantly nodular (18%), hyalinized/lamellar (46%), or mixed (32%), excepting two cases consisting entirely of metaplastic bone. Chronic inflammation, when present, was most often focal and perivascular in distribution. In one case, an excision after collagenase treatment showed myxoid change and increased stromal cellularity. Overall, these findings define the range of PD histology, particularly emphasizing that the calcification noted clinically nearly always represents bona fide metaplastic ossification. Such context will be of value in evaluating specimens prospectively, in light of changing practices and the use of new technologies for treatment.

A Reappraisal of Superficial Pleomorphic Liposarcoma.

OBJECTIVES: Superficial pleomorphic liposarcoma (PL) has a favorable prognosis compared to deeply seated PL. Given developments in the classification of lipomatous neoplasms, we reappraised a series of cases. METHODS: Retrospective clinicopathologic evaluation and genome-wide single-nucleotide polymorphism (SNP) microarray studies were performed for cases previously designated superficial PL. RESULTS: Four cases were identified (age, 48-70 years). Two were dermally confined, whereas two were superficial subcutaneous; no recurrences or metastases were reported. Tumors demonstrated pleomorphic spindled morphology with variable cellularity. Multivacuolated atypical lipoblasts were focal in 3 and abundant in 1. Dermal tumors demonstrated atypical cells within sclerotic collagen. Genome-wide SNP microarray studies revealed consistent gains and losses, including losses at the 13q14.2 locus encompassing RB1 and DLEU2 and deletion/disruption of the TP53 locus. Although subcutaneous examples showed genomic changes similar to deep PL, the dermal examples showed fewer genetic alterations, including changes reported in the spectrum of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT). All lacked MDM2 amplification. CONCLUSIONS: Careful integration of histologic and genetic features may improve classification of lipomatous neoplasms with atypia, allowing reclassification of some superficial PL as ASPLT.

New entities, new technologies, new findings: A review of the cytologic features of recently established subtypes of renal cell carcinoma.

Several new renal tumor types with distinctive pathologic, epidemiologic, and genetic signatures have recently been adopted in the fourth edition of the World Health Organization classification. In succeeding years, the cytologic features of most of these new types have been described, adding to the trend of increasing diagnostic accuracy for most common renal cell carcinoma subtypes and the important diagnostic role of cytologic sampling in the management and personalization of therapy. The current article reviews the cytologic findings from these recently established renal cell carcinoma subtypes. Emphasis is placed on cytologic diagnostic clues, confirmatory ancillary testing, salient differential diagnoses, and challenges that can be encountered in an attempt to render accurate interpretations in small samples.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings.

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

Clues to recognition of fumarate hydratase-deficient renal cell carcinoma: Findings from cytologic and limited biopsy samples.

BACKGROUND: Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) is rare and highly aggressive and is believed to arise mostly in the setting of hereditary leiomyomatosis-RCC syndrome with a germline mutation of FH. Because of the aggressiveness of these tumors and a frequent lack of ascertainable family history, these tumors may first present as metastases and be sampled by cytology. The cytologic findings of FH-deficient RCC have not previously been reported. METHODS: Cytologic and limited biopsy samples from patients with FH-deficient RCC were reviewed retrospectively. RESULTS: In total, 24 cytologic and limited biopsy samples from 19 patients (6 women and 13 men; age range, 22-69 years) who had FH-deficient RCC and metastasis at presentation were evaluated. These included 21 cytology samples ranging from malignant effusions (n = 7) to metastases (n = 11), to samples of primary kidney tumors (n = 3). The samples exhibited cells, often in clusters and abortive papillae, with voluminous, finely vacuolated cytoplasm and large, pleomorphic nuclei with prominent, viral inclusion-like nucleoli. A distinctive finding of peripheral cytoplasmic clearing frequently was apparent, and intranuclear cytoplasmic pseudoinclusions were less frequent. Of 7 cell block and biopsy samples, several of which represented sampling from the same patient, all demonstrated tissue fragments that had discernable morphologic patterns associated with FH-deficient RCC, including tubulocystic and intracystic papillary growth. CONCLUSIONS: Features characteristic and suggestive of FH-deficient RCC may be identified in cytologic and small biopsy samples. Although the current samples were identified retrospectively in well characterized cases of FH-deficient RCC, the authors argue that, with appropriate clinical correlation, these features are sufficiently distinctive to trigger recognition and confirmatory workup.

High grade infiltrative adenocarcinomas of renal cell origin: New insights into classification, morphology, and molecular pathogenesis.

Collecting duct carcinoma was described over 30 years ago as a renal tumor, based in the medullary collecting system, with tubulopapillary morphology, prominent infiltrative growth, and stromal desmoplasia. While diagnostic workup has always emphasized exclusion of upper tract urothelial carcinoma and metastatic adenocarcinoma to the kidney, the molecular era of renal cell carcinoma classification has enabled recognition of and provided tools for diagnosis of new entities in this morphologic differential. In this review, we consider these developments, with emphasis on renal medullary carcinoma, closely related renal cell carcinoma, unclassified with medullary phenotype, and fumarate hydratase-deficient renal cell carcinoma. Integration of ancillary studies with suggestive patterns of morphology is emphasized for practical implementation in contemporary diagnosis, and several emerging tumor types in the morphologic differential are presented.

GATA3 is a reliable marker for neuroblastoma in limited samples, including FNA Cell Blocks, core biopsies, and touch imprints.

BACKGROUND: Neuroblastomas (NBs) are the most common solid cancer of childhood and infancy; however, in poorly differentiated forms, they present diagnostic challenges. GATA3 has been implicated functionally in NB differentiation, and limited data support its use as an immunohistochemical biomarker for NBs in resection specimens. METHODS: GATA3 was tested retrospectively in 30 consecutive archival NB samples, including archival cytopathology needle cores and cell blocks (n = 6), scant surgical biopsy specimens and 2-mm NB tissue cores (n = 16), and air-dried touch imprints (n = 8) to evaluate the utility of this marker. Immunostaining was performed per the institutional standard, Clinical Laboratory Improvement Amendments-compliant automated staining protocol. GATA3 nuclear staining was scored qualitatively for its intensity and proportion of positivity. RESULTS: All 30 NB specimens showed diffuse nuclear positivity with GATA3. Each sample revealed either strong (n = 26) or moderate nuclear staining (n = 4) in more than 75% of NB cells, regardless of the presence or lack of stromata or necrosis or the degree of differentiation. CONCLUSIONS: GATA3 is a reliable diagnostic marker for NBs not only in scant/limited surgical specimens but also in cytologic samples, including air-dried touch imprints, which have previously been undescribed for this marker. Cancer Cytopathol 2017;125:940-6. © 2017 American Cancer Society.