Alvaro C. Laga

Improved detection suggests all Merkel cell carcinomas harbor Merkel polyomavirus

A human polyomavirus was recently discovered in Merkel cell carcinoma (MCC) specimens. The Merkel cell polyomavirus (MCPyV) genome undergoes clonal integration into the host cell chromosomes of MCC tumors and expresses small T antigen and truncated large T antigen. Previous studies have consistently reported that MCPyV can be detected in approximately 80% of all MCC tumors. We sought to increase the sensitivity of detection of MCPyV in MCC by developing antibodies capable of detecting large T antigen by immunohistochemistry. In addition, we expanded the repertoire of quantitative PCR primers specific for MCPyV to improve the detection of viral DNA in MCC. Here we report that a novel monoclonal antibody detected MCPyV large T antigen expression in 56 of 58 (97%) unique MCC tumors. PCR analysis specifically detected viral DNA in all 60 unique MCC tumors tested. We also detected inactivating point substitution mutations of TP53 in the two MCC specimens that lacked large T antigen expression and in only 1 of 56 tumors positive for large T antigen. These results indicate that MCPyV is present in MCC tumors more frequently than previously reported and that mutations in TP53 tend to occur in MCC tumors that fail to express MCPyV large T antigen.

Distinction of pulmonary small cell carcinoma from poorly differentiated squamous cell carcinoma: An immunohistochemical approach

Accurate morphologic distinction between small cell carcinoma and poorly differentiated squamous cell carcinoma has critical therapeutic significance, but can be limited by crush artifact, tumor necrosis, limited tumor representation, and overlapping morphologic features. We evaluated a panel of antibodies for their efficacy in distinguishing between these neoplasms. Formalin-fixed paraffin-embedded tissue sections of small cell carcinomas and poorly differentiated squamous cell carcinomas underwent immunohistochemical staining with antibodies to thyroid transcription factor-1, p63, high molecular weight keratin, and p16(INK4A). Of 28 small cell carcinomas, 26 (93%) small cell carcinomas showed diffuse moderate or strong staining for thyroid transcription factor-1 with no staining for high molecular weight keratin and p63. In contrast, 27/28 (96%) poorly differentiated squamous cell carcinomas manifested opposite immunoreactivities, with diffuse moderate or strong staining for high molecular weight keratin and p63, and no or minimal staining for thyroid transcription factor-1. In two additional cases originally interpreted as small cell carcinoma, high molecular weight keratin highlighted small numbers of neoplastic large cells, leading to reclassification as combined small cell and non-small cell carcinomas. p16(INK4A) expression varied widely in poorly differentiated squamous cell carcinomas, but was consistently moderate or strong and diffuse in small cell carcinomas, and proved helpful in the two thyroid transcription factor-1-negative small cell carcinomas. This study demonstrates that a panel consisting of antibodies to thyroid transcription factor-1, p63, high molecular weight keratin, and p16(INK4A) is highly effective for distinguishing between small cell carcinoma and poorly differentiated squamous cell carcinoma. This panel also facilitates diagnosis of combined small cell and non-small cell carcinomas.

Genomic Analysis of Metastatic Cutaneous Squamous Cell Carcinoma

Purpose: A rare 5% of cutaneous squamous cell carcinomas (cSCC) metastasize, lack FDA-approved therapies, and carry a poor prognosis. Our aim was to identify recurrent genomic alterations in this little-studied population of metastatic cSCCs. Experimental Design: We performed targeted sequencing of 504 cancer-associated genes on lymph node metastases in 29 patients with cSCC and identified mutations and somatic copy-number alterations associated with metastatic cSCC. We determined significantly mutated, deleted, and amplified genes and associated genomic alterations with clinical variables. Results: The cSCC genome is heterogeneous with widely varying numbers of genomic alterations and does not appear to be associated with human papillomavirus. We found previously identified recurrently altered genes (TP53, CDKN2A, NOTCH1/2) but also a wide spectrum of oncogenic mutations affecting RAS/RTK/PI3K, squamous differentiation, cell cycle, and chromatin remodeling pathway genes. Specific mutations in known oncogenic drivers and pathways were correlated with inferior patient outcomes. Our results suggest potential therapeutic targets in metastatic cSCC, including PIK3CA, FGFR3, BRAF, and EGFR, similar to those reported in SCCs of the lung and head and neck, suggesting that clinical trials could be developed to accrue patients with SCCs from multiple sites of origin. Conclusions: We have genomically characterized a rare cohort of 29 metastatic cSCCs and identified a diverse array of oncogenic alterations that can guide future studies of this disease. Clin Cancer Res; 21(6); 1447–56. ©2015 AACR.

Expression of The Embryonic Stem Cell Transcription Factor SOX2 in Human Skin : Relevance to Melanocyte and Merkel Cell Biology

SOX2 is a gene located on chromosome 3q26.33 that encodes a transcription factor important to maintenance of embryonic neural crest stem cell pluripotency. We have identified rare SOX2-immunoreactive cells in normal human skin at or near the established stem cell niches. Three subsets of SOX2-positive cells were defined in these regions: those expressing only SOX2 and those that co-expressed SOX2 and either CK20 or microphthalmia-associated transcription factor, which are consistent with dichotomous differentiation of SOX2-expressing precursors along neuroendocrine (Merkel cell) or melanocytic lines, respectively. Examination of Merkel cell carcinomas confirmed nuclear SOX2 expression in this tumor type. In human patient melanoma, strong nuclear expression of SOX2 was noted in a subset of tumors, and the ability to detect SOX2 in lesional cells significantly correlated with primary tumor thickness in a survey cohort. To assess the potential role of SOX2 in melanoma growth, an in vivo tumorigenesis assay was used. Whereas SOX2 knockdown failed to influence proliferation of cultured melanoma cells in vitro, tumor xenografts generated with the SOX2-knockdown cell line showed significant decrease in mean tumor volume as compared with controls. In aggregate, these findings suggest that SOX2 is a novel biomarker for subpopulations of normal skin cells that reside in established stem cell niches and that might relate to Merkel cell and melanocyte ontogeny and tumorigenesis.

SOX2 contributes to melanoma cell invasion

The mechanisms of melanoma invasion are poorly understood despite extensive inquiry. SRY (sex determining region Y)-box 2 (SOX2) is an embryonic stem cell transcription factor that has recently been discovered to be expressed in human melanoma where it is associated with dermal invasion and primary tumor thickness. To assess the potential role of SOX2 expression in melanoma invasion, we examined patient melanomas and humanized melanoma xenografts, and noted preferential SOX2 expression in cells that interfaced and infiltrated dermal stroma. Experimental knockdown (KD) of SOX2 mRNA and protein in A2058 melanoma cells with high constitutive SOX2 expression resulted in 4.5-fold decreased invasiveness in vitro compared with controls (P<0.0001). Conversely, when G361 cells that normally express low SOX2 were transduced to overexpress SOX2 mRNA and protein, a 3.8-fold increase in invasiveness was observed (P=0.0004). Among 84 invasion-related genes, RT-PCR screening revealed that SOX2 KD resulted in striking decrease in matrix metalloproteinase-3 (MMP-3), an endopeptidase associated with cleavage of the extracellular matrix. Quantitatively, SOX2 KD diminished MMP-3 mRNA by 87.8%. MMP-3 KD in SOX2-expressing A2058 cells served to inhibit invasion, although to a lesser degree than SOX2 KD. Finally, immunostaining of patient and xenograft melanomas revealed coordinate SOX2 and MMP-3 expression in regions of stromal infiltration. These data implicate SOX2 expression in melanoma invasion, and suggest a role for MMP-3 as one potential mediator of this process.

SOX2 and nestin expression in human melanoma: an immunohistochemical and experimental study

Abstract:  SOX2 is an embryonic neural crest stem‐cell transcription factor recently shown to be expressed in human melanoma and to correlate with experimental tumor growth. SOX2 binds to an enhancer region of the gene that encodes for nestin, also a neural progenitor cell biomarker. To define further the potential relationship between SOX2 and nestin, we examined co‐expression patterns in 135 melanomas and 37 melanocytic nevi. Immunohistochemical staining in 27 melanoma tissue sections showed an association between SOX2 positivity, spindle cell shape and a peripheral nestin distribution pattern. In contrast, SOX2‐negative cells were predominantly epithelioid, and exhibited a cytoplasmic pattern for nestin. In tissue microarrays, co‐expression correlated with tumor progression, with only 11% of nevi co‐expressing SOX2 and nestin in contrast to 65% of metastatic melanomas, and preliminarily, with clinical outcome. Human melanoma lines that differentially expressed constitutive SOX2 revealed a positive correlation between SOX2 and nestin expression. Experimental melanomas grown from these respective cell lines in murine subcutis and dermis of xenografted human skin maintained the association between SOX2‐positivity, spindle cell shape, and peripheral nestin distribution. Moreover, the cytoplasmic pattern of nestin distribution was observed in xenografts generated from SOX2‐knockdown A2058 melanoma cells, in contrast to the periperhal nestin pattern seen in tumors grown from A2058 control cells transfected with non‐target shRNA. In aggregate, these data further support a biologically significant linkage between SOX2 and nestin expression in human melanoma.

Histopathologic Spectrum of Psoriasiform Skin Reactions Associated With Tumor Necrosis Factor-α Inhibitor Therapy. A Study of 16 Biopsies

Tumor necrosis factor (TNF)-α inhibitors (anti-TNF-α biologic drugs), currently used to treat different autoimmune conditions, may be associated with cutaneous drug reactions. New onset or worsening of psoriasis and psoriasis-like reactions have been reported in these patients. However, not much is known about the different histopathologic patterns of such skin lesions. The aim of this study was to evaluate the pathologic spectrum of clinically papulosquamous to pustular “psoriasiform” lesions in this setting. Sixteen biopsies from 9 patients on anti-TNF-α therapy for rheumatoid arthritis (n = 7), Crohn disease (n = 1), and Behçet disease (n = 1) who developed a “psoriasiform” skin rash during treatment were included in this study. None of the patients had history of psoriasis. Five patients (10 biopsies) showed a psoriasis-like pattern that varied from that seen in guttate lesions (4 biopsies), to well-established plaques (3 biopsies) to pustular psoriasis (3 biopsies). Three patients (4 biopsies) showed an interface/lichenoid dermatitis mimicking lichen planus. Two patients (2 biopsies) showed features of pustular folliculitis. Eosinophils varied from none (2 biopsies) to scattered (7 biopsies) to numerous (7 biopsies). Plasma cells were present in most cases. All pustular lesions had negative cultures. In conclusion, anti-TNF drugs elicit a spectrum of cutaneous reactions that go beyond the classical eosinophilic-rich hypersensitivity reaction and may closely mimic primary dermatitis. In addition to psoriasis-like lesions, lichen planus-like dermatitis and sterile pustular folliculitis should be included in the list of anti-TNF-α-related drug reactions. Because the different histopathologic findings may be subtle, clinical correlation is crucial to make the diagnosis.

Myopericytoma: report of two cases associated with trauma

Myopericytoma is a rare, recently described tumor demonstrating a hemangiopericytoma‐like vascular pattern. We present two cases of myopericytoma associated with trauma: a 64‐year‐old man who developed several nodules on his nose four months after sustaining multiple abrasions to his forehead and nose, and a 72‐year‐old woman with a solitary growth in the alveolar ridge of unknown duration. Biopsy specimens of the lesions in both cases demonstrated a striking concentric perivascular proliferation of bland spindle‐shaped pericytic cells characteristic of myopericytoma. Despite sharing morphologic features with angioleiomyoma, myofibroma and glomus tumor, myopericytoma is thought to represent a distinct perivascular myoid neoplasm of skin and soft tissues. The tumor is characterized by a radial and perivascular arrangement of ovoid, spindled to round neoplastic cells that are immunoreactive to alpha‐smooth muscle actin, often for h‐caldesmon as well as smooth muscle myosin‐heavy chain, and usually negative for desmin antibodies. Most cases of myopericytoma are benign, however, local recurrence and malignancy have recently been reported, Myopericytoma can be multifocal involving a single or multiple anatomic regions, and tends to occur in dermal and superficial soft tissues of adults primarily on the extremities. Our cases are unusual examples of myopericytoma manifesting as multiple nodules on the nose, and a solitary growth on the buccal mucosa after trauma.

Prognostic Significance of Cyclooxygenase 2 Expression in 259 Cases of Non-Small Cell Lung Cancer

CONTEXT Previous studies report that increased expression of cyclooxygenase 2 (COX-2) correlates with poor clinical outcome in several malignancies, including non- small cell lung carcinoma (NSCLC). Cyclooxygenase 2 inhibitors have been reported to effectively inhibit carcinogenesis in colon cancer experimental models. OBJECTIVE We examined COX-2 expression in 259 cases of NSCLC to evaluate its prognostic significance. DESIGN Sections of NSCLC from patients with a median 5-year follow-up were immunostained with COX-2 monoclonal antibody (1:150) using the Dako mouse EnVision;pl system. Extent of COX-2 expression in neoplastic cells was recorded as follows: 0, 0% to 10% of cells positive; 1, 11% to 33% positive; 2, 34% to 66% positive; and 3, more than 66% positive. Intensity was scored as either increased (+) or not increased (-), compared to internal control smooth muscle and endothelial cells. Kaplan-Meier analysis was used to assess the relationship between survival and COX-2 expression, using the log-rank test for statistical significance. RESULTS No relationship was found between the extent and/or the intensity of COX-2 expression and patient survival when the entire cohort was considered. However, when separately analyzed according to disease stage and intensity of COX-2 expression, a significant relationship (P = .03) between increased COX-2 expression and shortened patient survival was found only in patients with stage I and II NSCLC. CONCLUSIONS To our knowledge, this is the largest series of NSCLCs in which COX-2 has been investigated as a prognostic marker. The findings in this large series support previous studies of smaller cohorts that reported that increased COX-2 expression predicts poor outcome in patients with early-stage NSCLC.

Review and Update of Uncommon Primary Pleural Tumors: A Practical Approach to Diagnosis

OBJECTIVE We address the current classifications and new changes regarding uncommon primary pleural tumors. Primary pleural tumors are divided according to their behavior and are discussed separately as benign tumors, tumors of low malignant potential, and malignant neoplasms. DATA SOURCES Current literature concerning primary pleural neoplasms was collected and reviewed. STUDY SELECTION Studies emphasizing clinical, radiological, or pathologic findings of primary pleural neoplasms were obtained. DATA EXTRACTION Data deemed helpful to the general surgical pathologist when confronted with an uncommon primary pleural tumor was included in this review. DATA SYNTHESIS Tumors are discussed in 3 broad categories: (1) benign, (2) low malignant potential, and (3) malignant. A practical approach to the diagnosis of these neoplasms in surgical pathology specimens is offered. The differential diagnosis, including metastatic pleural neoplasms, is also briefly addressed. CONCLUSIONS Uncommon primary pleural neoplasms may mimic each other, as well as mimic metastatic cancers to the pleura and diffuse malignant mesothelioma. Correct diagnosis is important because of different prognosis and treatment implications for the various neoplasms.