Faculty Bibliography

It is well known that fibrous dysplasia (FD) is characterized by the presence of activating mutations involving G-nucleotide binding protein-α subunit (GNAS) involving codon R201 and rarely codon 227 with a mutation frequency between 45% and 93%. Herein, we investigate the sensitivity of detection of GNAS mutations in exons 8 and 9 using a standard and a highly sensitive locked nucleic acid polymerase chain reaction (LNA-PCR) sequencing in 52 cases of FD. In view of the recent report of GNAS mutations in a small number of low-grade osteosarcomas, we also tested in addition 12 cases of low-grade osteosarcomas. GNAS exon 8 mutations p.R201H (31%), p.R201C (15%), and p.R201S (2%) were identified in 50% of FD cases. LNA-PCR sequencing identified only 1 positive case within the mutation negative cases tested by standard PCR and Sanger sequencing. No mutations were identified in any of the low-grade osteosarcomas by standard and LNA-PCR sequencing. There was no association between age, site, size, specimen type, and mutational status. No exon 9 or codon 227 mutations were identified in any of tested cases. There was a significant difference in the sensitivity of the assay between decalcified and nondecalcified FDs (31% vs. 70%, P=0.002). LNA-PCR has no added value in enhancing detection sensitivity for GNAS mutations in FD. In addition to decalcification, innate somatic mosaicism contributes to the decreased sensitivity in mutation detection.

Monoclonal antibodies against the immune checkpoint programmed cell death receptor 1 (PD-1) improve the hosts' antitumor immune response and have showed tremendous promise in the treatment of advanced solid tumors and hematologic malignancies. Reports of serious autoimmune dermatologic toxicities from immune checkpoint blockade therapy, however, are emerging. We report our experience with five patients who presented with pruritic vesicles and blisters on the skin while treated with anti-PD-1 antibody immunotherapy with either nivolumab or pembrolizumab. Four of the patients' skin biopsies revealed subepidermal bullae with immunohistochemical study for type IV collagen labeling the floor of the blister cavity and direct immunofluorescence studies (in three of the four patients tested) decorated linear IgG and C3 immune deposits on the blister roof, diagnostic of bullous pemphigoid. One patient developed bullous erythema multiforme. All patients had partial or complete resolution of skin lesions following treatment with systemic corticosteroid and cessation of checkpoint blockade. Recognition and treatment of rare immune-related bullous dermatologic toxicities will become increasingly important as more patients are treated with effective and newer immune checkpoint blockade therapy.

Angiogenesis plays a crucial role in melanoma metastasis and progression. In recent years, numerous studies have investigated the prognostic and clinical significance of this phenomenon, and the development of molecular techniques has enabled us to achieve a better understanding of angiogenesis in melanoma. Herein, we review the current state of knowledge regarding angiogenesis in melanoma, including the pathophysiological, histological and immunohistochemical aspects of this phenomenon. We also review the molecular pathways involved in angiogenesis and the interplay between different components that might be manipulated in the future development of efficient targeted therapies. Recently developed targeted antiangiogenic therapies in clinical trials and included in the treatment of advanced-stage melanoma are also reviewed.

Extraskeletal osteosarcoma (ESOSA) is a rare soft tissue neoplasm representing <5% of osteosarcomas and <1% of all soft-tissue sarcomas. Herein, we investigate the clinicopathological and molecular features of ESOSA and explore potential parameters that may affect outcome. Thirty-two cases were retrieved and histomorphology was reviewed. Clinical history and follow-up were obtained through electronic record review. DNA from formalin-fixed paraffin-embedded (FFPE) tissue was extracted and processed from 27 cases. Genome-wide DNA copy number (CN) alterations and allelic imbalances were analyzed by single nucleotide polymorphism array using Affymetrix OncoScan FFPE Assay. Massive high-throughput deep parallel sequencing was performed using a customized panel targeting 410 cancer genes. Log rank, Fisher's exact test and Cox proportional hazards were used for statistical analysis. In this series of 32 patients (male n = 12, female n = 20), the average age was 66 years (19-93) and median follow up was 24 months (range 6-120 months). Frequent genomic alterations included CN losses in tumour suppressor genes including CDKN2A (70%), TP53 (56%) and RB1 (49%). Mutations affecting methylation/demethylation, chromatin remodeling and WNT/SHH pathways were identified in 40%, 27%, and 27%, respectively. PIK3CA and TERT promoter variant mutations were identified in 11% of the cases. Cases harbouring simultaneous TP53 and RB1 biallelic CN losses were associated with worse overall survival and local recurrence (p = 0.04, p = 0.02, respectively). CDKN2A losses and positive margins were also associated with worse overall survival (p = 0.002; p = 0.03, respectively). Our findings suggest that age above 60, positive margin status, simultaneous biallelic TP53 and RB1 losses and CDKN2A loss are associated with a worse outcome in ESOSA. Comparison between conventional paediatric osteosarcoma and ESOSA shows that, while both share genetic similarities, there are notable dissimilarities and mechanistic differences in the molecular pathways involved in ESOSA.

Epithelial glandular differentiation in dedifferentiated chondrosarcoma has not been described. Our patient was a 64-year-old man with a history of prostate cancer status post-radiation and hormonal therapy. On screening bone scan, he was found to have increased uptake in his right femoral shaft. Biopsy revealed intermediate-grade conventional chondrosarcoma. Subsequent femoral resection was remarkable for an intermediate-grade chondrosarcomatous component juxtaposed to an area composed of anastomosing nests and cords of malignant epithelial cells showing nuclear atypia and increased mitotic activity. A fibroblastic-appearing spindle cell population was intimately associated with the epithelial cells. The epithelial cells labeled with 34bE12, AE1/AE3, EMA, and Vimentin (both spindled and epithelial components) while being negative for prostate-specific antigen, prostate specific acid phosphatase, cytokeratin 20, thyroid transcription factor-1, and CDX2. The patient developed local recurrence 9 months after the initial resection but has had no metastatic disease and consistently undetectable prostate-specific antigen levels. Deep parallel sequencing of the dedifferentiated component showed a nonsynonymous mutation at exon 4 of IDH1 gene at codon R132 leading to a substitution of arginine, with serine confirming glandular differentiation in dedifferentiated chondrosarcoma.

Dedifferentiated liposarcoma represents a form of liposarcoma composed of a non-lipogenic sarcoma associated with well-differentiated liposarcoma. The prognostic significance of histological grading of the dedifferentiated component remains to be elucidated due to vague grading criteria employed in previous studies. Molecular markers of tumor behavior, including amplification levels of murine double minute-2 (MDM2) and cyclin-dependent kinase-4 (CDK4) genes, have been explored in a limited number of cases. Here we investigate whether 'Fédération Nationale des Centres de Lutte Contre le Cancer' (FNCLCC) grade and MDM2 gene amplification levels have prognostic value in dedifferentiated liposarcoma in terms of local recurrence and disease-specific survival. Fifty cases were retrieved, reviewed and FNCLCC grade was scored for the dedifferentiated component. Testing for MDM2 gene amplification was performed by fluorescence in situ hybridization. Amplification was categorized as high level (≥20 copies) and as low level (<20 copies). Follow-up data was obtained through chart review. Log-rank test and Cox proportional hazard models were used to determine the effect of grade and level of MDM2 amplification on outcomes. Our series includes 50 patients (male n=28, female n=22) with an average age of 63 years (range, 28-88) and a median follow-up of 28 months (range, 2-120). Tumors were graded as grade 1 (6%), grade 2 (58%), and grade 3 (36%). When adjusted for age, sex, site, tumor size, and margin status, grade 3 patients had a higher recurrence rate than grades 1 and 2 (HR=2.07, 95% CI: 1.24, 7.62; P=0.015). Patients with high-level MDM2 amplification had higher recurrence rate on univariate analysis (P=0.028), but not on multivariate analysis (HR=1.69, 95% CI: 0.73, 3.94; P=0.221). FNCLCC grade 3 dedifferentiation confers a worse prognosis in dedifferentiated liposarcoma in terms of local recurrence. MDM2 amplification level remains a useful diagnostic tool in dedifferentiated liposarcoma, but has no prognostic value in terms of local recurrence.

Giant cell tumors of bone (GCTs) are generally benign, locally aggressive neoplasms that rarely metastasize. The beta subunit of human chorionic gonadotropin (beta-hCG) is expressed in syncytiotrophoblasts and several nongynecologic neoplasms but has not been described in GCT. At our institution, we observed cases of elevated beta-hCG in patients with GCT leading to diagnostic difficulty and in one case, concern for metastatic choriocarcinoma. This study aims to determine the frequency of beta-hCG expression in GCT and any relationship to clinical aggressiveness. We evaluated tissue expression of beta-hCG by immunohistochemistry with 58% of cases staining for beta-hCG. Additionally, 2 of 11 patients with available serum and/or urine beta-hCG measurements demonstrated elevated beta-hCG due to tumor. It is important to be aware of beta-hCG expression by GCT and the potential for elevated urine and serum beta-hCG levels in patients with GCT so as to avoid misdiagnosis of pregnancy or gestational trophoblastic disease.

Cutaneous carcinosarcoma (CCS) is an extraordinarily rare neoplasm with a biphasic morphological pattern exhibiting both epithelial and sarcomatoid components. Although its histogenesis and biological aspects remain poorly understood, previous studies have postulated that this tumor may arise from single cancer stem cells which subsequently differentiate into distinct tumor lineages. In this study, we explored a wide array of mutational hot spot regions, through high-depth next-generation sequencing of 47 cancer-associated genes in order to assess the mutational landscape of these tumors and investigate whether the epithelial and mesenchymal components shared the same genetic signatures. Results from this study confirm that despite their striking phenotypic differences, both elements of this infrequent tumor indeed share a common clonal origin. Additionally, CCS appears to embrace a heterogeneous spectrum with specific underlying molecular signatures correlating with the defining epithelial morphotype, with those carcinosarcomas exhibiting a squamous cell carcinoma epithelial component exhibiting diverse point mutations and deletions in the TP53 gene, and those with a basal cell carcinoma morphotype revealing a more complex mutational landscape involving several genes. Also, the fact that our findings involve several targetable gene pathways suggests that the underlying molecular events driving the pathogenesis of CCS may represent future potential targets for personalized therapies.