Next Generation Sequencing analysis suggests varied multistep mutational pathogenesis for Endocrine Mucin Producing Sweat Gland Carcinoma with comments on INSM1 and MUC2 suggesting a conjunctival origin

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a low-grade eyelid tumor. Small biopsies and insensitive immunohistochemistry predispose to misdiagnosis. We aimed to identify clarifying immunohistochemical and/or molecular markers. Clinicopathologic data (22 cases) was reviewed. Immunohistochemistry (Insulinoma-associated protein-1(INSM1), BCL-2, MUC2, MUC4, androgen-receptor, Beta-catenin, MCPyV) and next generation sequencing (MSK-IMPACT, 468 genes) was performed (3 cases). Female (n=15) and male (n=7) patients, mean-age 71.8 years (53-88), had eyelid/periorbital tumors (>90%) with mucin-containing solid/cystic neuroendocrine pathology. Immunohistochemistry (INSM1, BCL2, androgen-receptor, RB1, Beta-catenin) was diffusely-positive (5/5), MUC2 partial, MUC4 focal, and MCPyV negative. MSK-IMPACT identified 12 single-nucleotide-variants and one in-frame deletion in 3 cases, each with DNA damage response/repair (BRD4, PPP4R2, RTEL1) and tumor-suppressor pathway (BRD4, TP53, TSC1, LATS2) mutations. Microsatellite instability, copy number alterations, and structural alterations were absent. INSM1 and MUC2 are positive in EMPSGC. MUC2 positivity suggests conjunctival origin. Multistep pathogenesis involving DNA damage repair and tumor-suppressor pathways may be implicated.

Lung-only melanoma: UV mutational signature supports origin from occult cutaneous primaries and argues against the concept of primary pulmonary melanoma

Primary pulmonary melanoma (PPM) is an entity recognized by the thoracic WHO classification. However, given the absence of native melanocytes in the lung and the known phenomenon of regression of cutaneous melanomas, the existence of PPM has remained controversial. Herein we investigate clinicopathologic and genomic features of lung-only melanomas with the goal to clarify their site of origin. We identified 10 melanomas involving exclusively lung with no current or previous cutaneous, uveal, or mucosal primaries. Four patients had solitary lesions with mean size of 5.1 cm (range 3.0-10.1 cm), meeting the criteria of PPM. Four patients had 2-3 lesions and 2 patients had >10 lesions. All cases underwent targeted next-generation sequencing interrogating up to 468 cancer genes, which revealed mean tumor mutation burden of 42.6 per megabase (range 1.8 to 126) and frequent mutations involving BRAF, NRAS, NF1, KIT, and KRAS - a genomic profile typical of UV-associated cutaneous melanoma. Mutational signature was assessable for eight cases harboring >20 mutations. This revealed that all evaluable cases harbored a dominant UV signature. In addition, one nonevaluable case harbored a GG > AA TERT promoter variant that is highly specific for UV-mutagenesis. As control groups, using the same methodology, a dominant UV signature was identified in 97% (470/486) of cutaneous melanomas, whereas no lung adenocarcinoma (n = 291) exhibited this signature. Notably, the clinical and pathologic features of solitary melanomas, especially those with large size and epithelioid morphology, closely mimicked primary lung carcinomas, highlighting a major potential for misdiagnosis. In conclusion, presence of a UV signature provides direct evidence that nearly all lung-only melanomas in this series, including solitary lesions meeting the strict criteria of PPM, represent metastases from occult cutaneous melanomas. This suggests that lung-only melanomas should be considered as likely metastatic even in the absence of a known primary melanoma elsewhere.

Incompletely excised lentigo maligna melanoma is associated with unpredictable residual disease: clinical features and the emerging role of reflectance confocal microscopy

BACKGROUND

Lentigo maligna/lentigo maligna melanoma (LM/LMM) poses a treatment and surgical challenge given unpredictable subclinical extension resulting in incomplete excision.

OBJECTIVES

To describe the demographic, clinical and pathologic characteristics of incompletely excised LM/LMM. To evaluate the potential role of reflectance confocal microscopy (RCM).

PATIENTS AND METHODS

A retrospective review of a melanoma database at a tertiary cancer centre for patients referred with 'incompletely excised LM/LMM' or 'incompletely excised melanoma' between October 2006 and July 2017. We recorded clinical and pathological data and surgical margins needed to clear the residual LM/LMM. The second part consisted of a prospective cohort of patients in which RCM was performed when presenting with incompletely excised LM/LMM.

RESULTS

We included a total of 67 patients (retrospective + prospective cohort); mean age was 64.9 (standard deviation: 11.3) years and 52.2% were males. For the retrospective cohort (n = 53), the mean scar size was 3.4 cm. The average initial margins excised prior to presentation were 4.8 mm (range 3-7 mm). The average additional margin needed to clear the residual, incompletely excised LM/LMM was 7.8 mm. For the prospective cohort (n = 14), there were no differences in age, gender or size when compared to the retrospective cohort. RCM had a diagnostic accuracy of 78.6%, a sensitivity of 90.9%, a specificity of 33.3% and a positive predictive value of 83.3% for the detection of incompletely excised LM/LMM.

CONCLUSIONS

Incompletely excised LM/LMM is a poorly characterized clinical-pathological scenario that may require considerable extra margins for microscopic clearance. RCM may emerge as a valuable tool for the evaluation of patients with incompletely excised LM/LMM.

Clinical and dermoscopic features of Fibroepithelioma of Pinkus: case series with an emphasis on hypopigmented to pink lines intersecting at acute angles

Fibroepithelioma of Pinkus (FEP) is a subtype of basal cell carcinoma (BCC) that can clinically resemble intradermal nevi (IDN) and fibromas. We performed a retrospective review of consecutively biopsied lesions confirmed to be FEP on histopathology diagnosed from January 1, 2008 to April 8, 2019. Clinical (n = 48), contact non-polarized dermoscopy (NPD) (n = 44), and contact polarized dermoscopy (PD) (n = 22) images from 36 patients were reviewed. Mean age was 64.5 years (SD 15.1 years, range 24-86 years) at diagnosis of first FEP lesion. Most lesions were located on the torso (n = 28, 58.3%), followed by the lower extremity (n = 9, 18.8%). The most common differential diagnoses at the time of biopsy included BCC (n = 40) and nevus (other than IDN, n = 5). Clinically, FEP were pink (95.8%), scaly (66.7%) papules (77.1%) displaying disrupted skin markings (62.5%) and absence of hair follicles (87.5%). NPD revealed serpentine (97.7%), dotted (81.8%), or polymorphous vessels (86.4%), and hypopigmented to pink lines intersecting at acute angles (HPLA) (52.3%). PD demonstrated serpentine (95.5%), dotted (86.4%), or polymorphous vessels (81.8%), shiny white lines (50.0%), and HPLA (59.1%). Classic features of BCC such as arborizing vessels (n = 2), ulceration (n = 1), shiny white blotches and strands (n = 1), blue-gray ovoid nest (n = 1), and leaf-like areas (n = 1) were uncommon. FEP often presents as scaly, erythematous papules with disrupted skin markings and absence of hair follicles. Dermoscopy reveals polymorphous vessels with shiny white lines and HPLA.

Sentinel lymph node biopsy predicts systemic recurrence in digital papillary adenocarcinoma

BACKGROUND AND OBJECTIVES

Digital papillary adenocarcinoma (DPA) is a rare, aggressive neoplasm of sweat gland origin. It can recur at local, regional, or distant sites. There is limited knowledge about the role of sentinel lymph node biopsy (SLNB) in predicting recurrence in these patients. We present our experience with this uncommon tumor to evaluate the role of SLNB in predicting outcome.

METHODS

Medical records of all patients who underwent surgical treatment for biopsy-proven upper extremity DPA at the study institution were reviewed. Descriptive statistics and Fisher's exact test were used to analyze data.

RESULTS

Twenty-one patients were identified. Most patients were male (71%), and the median age was 51 years. SLNB was performed in 18 patients; three were positive for nodal metastatic disease (17%). At a median follow-up of 53 months, there were no local recurrences and two cases of systemic recurrence. No patient with a negative sentinel lymph node has evidence of metastasis or recurrence. Fisher's exact test demonstrated a significant association between a positive SLNB and recurrence (P = .02).

CONCLUSION

SLNB revealed metastatic disease in 17% of patients with DPA and appears to predict systemic recurrence in this small series.

Replacement and desmoplastic histopathological growth patterns in cutaneous melanoma liver metastases: frequency, characteristics, and robust prognostic value

Among visceral metastatic sites, cutaneous melanoma (CM) metastasises initially to the liver in ~14-20% of cases. Liver metastases in CM patients are associated with both poor prognosis and poor response to immunotherapy. Histopathological growth patterns (HGPs) of liver metastases of the replacement and desmoplastic type, particularly from colorectal cancer and uveal melanoma (UM), may impart valuable biological and prognostic information. Here, we have studied HGP in 43 CM liver metastases resected from 42 CM patients along with other prognostic factors from three institutions. The HGPs (replacement, desmoplastic, pushing) were scored at the metastasis-liver interface with two algorithms: (1) 100% desmoplastic growth pattern (dHGP) and any (≥1%) replacement pattern (any-rHGP) and (2) >50% dHGP, >50% rHGP or mixed (<50% dHGP and/or rHGP, pushing HGP). For 1 patient with 2 metastases, an average was taken to obtain 1 final HGP yielding 42 observations from 42 patients. 22 cases (52%) had 100% dHGP whereas 20 (48%) had any replacement. Cases with rHGP demonstrated vascular co-option/angiotropism. With the development of liver metastasis, only rHGP (both algorithms), male gender and positive resection margins predicted diminished overall survival (p = 0.00099 and p = 0.0015; p = 0.034 and p = 0.024 respectively). On multivariate analysis, only HGP remained significant. 7 of 42 (17%) patients were alive with disease and 21 (50%) died with follow-up after liver metastases ranging from 1.8 to 42.2 months (mean: 20.4 months, median: 19.0 months). 14 (33%) patients with previously-treated metastatic disease had no evidence of disease at last follow up. In conclusion, we report for the first time replacement and desmoplastic HGPs in CM liver metastases and their prognostic value, as in UM and other solid cancers. Of particular importance, any rHGP significantly predicted diminished overall survival while 100% dHGP correlated with increased survival. These results contribute to a better understanding of the biology of CM liver metastases and potentially may be utilised in managing patients with these metastases.

[The role of new molecular tests in the diagnosis of melanoma in a setting of congenital nævus in an infant]

INTRODUCTION

Congenital and infantile melanomas are extremely rare. We report a case of a child presenting at birth with a giant congenital nevus complicated by melanoma and on long-term follow-up with exploration using new immunohistochemistry and molecular biology tools.

OBSERVATION

A new-born girl presented at birth with a large congenital cervico-mandibular tumour with para-pharyngeal extension and underlying osteolysis. At 7 months, histology and immunohistochemistry of the operative specimen revealed nodules with atypical features (mitotic figures, necrosis and positive expression of KI67 and P53 in approximatively 50 % of the melanocytic nuclei). A diagnosis was made of infantile melanoma associated with congenital nevi. Repeated surgery and monitoring (clinical and imaging) were performed. At the age of 7 years, as there was no evidence of metastatic lesions, further analyses were performed on the initial operative specimen. Investigation of transcription factor expression using immunohistochemistry, comparative genomic hybridization and histology-guided mass spectrometry, although suspect, did not in itself support a diagnosis of melanoma. Finally, at the age of 7 years, hepatic and pulmonary metastases were reported. Despite combined immunotherapy with ipilimumab and nivolumab, the child died 5 months later.

CONCLUSION

This case illustrates the complexity of diagnosis of infantile melanoma and the risk of metastatic involvement long after the initial diagnosis. Diagnosis may be difficult and necessitates expert advice and the application of several recent methods to reach a conclusion and initiate appropriate treatment.

Tumor Board Conferences for Multidisciplinary Skin Cancer Management: A Survey of US Cancer Centers

Background: Tumor board conferences (TBCs) are used by oncologic specialists to review patient cases, exchange knowledge, and discuss options for cancer management. These multidisciplinary meetings are often a cornerstone of treatment at leading cancer centers and are required for accreditation by certain groups, such as the American College of Surgeons' Commission on Cancer. Little is known regarding skin cancer TBCs. The objective of this study was to characterize the structure, function, and impact of existing skin cancer TBCs in the United States. Methods: A cross-sectional online survey was administered to physician leaders of skin cancer TBCs at NCI-designated Comprehensive and Clinical Cancer Centers. Results: Of the 59 centers successfully contacted, 14 (24%) reported not having a conference where skin cancer cases were discussed, and 45 (76%) identified 53 physician leaders. A total of 38 physicians (72%) completed the survey. Half of the meeting leaders were medical and/or surgical oncologists, and dermatologists led one-third of meetings. TBCs had a moderate to significant impact on patient care according to 97% of respondents. All respondents indicated that the meetings enhanced communication among physicians and provided an opportunity for involved specialists and professionals to discuss cases. The most frequently cited barrier to organizing TBCs was determining a common available date and time for attendees (62%). The most common suggestion for improvement was to increase attendance, specialists, and/or motivation. Conclusions: Results showed overall consistency in meeting structure but variability in function, which may be a reflection of institutional resources and investment in the conference. Future directions include defining metrics to evaluate changes in diagnosis or management plan after tumor board discussion, attendance, clinical trial enrollment, and cost analysis. Results of this survey may aid other institutions striving to develop and refine skin cancer TBCs.

Extramammary Paget disease shows differential expression of B7 family members B7-H3, B7-H4, PD-L1, PD-L2 and cancer/testis antigens NY-ESO-1 and MAGE-A

Extramammary Paget disease (EMPD) is a rare cutaneous adenocarcinoma of the anogenital region most commonly treated with surgical excision. Surgical margin clearance is often problematic and recurrence rates remain high indicating the need for additional therapeutic options. Topical immunomodulators have been used with reported success suggesting EMPD may respond to other immunotherapies. This study investigates EMPD protein expression of targetable B7 family members and cancer/testis antigens (CTAs) B7-H3, B7-H4, PD-L1, PD-L2, MAGE-A, and NY-ESO-1 and components of antigen presenting machinery B2M and MHC-I. Fifty-seven specimens from 48 patients (31 female and 17 male), representing in situ, invasive, and metastatic disease of primary and secondary origin were stained and scored (627 total slides). The percentage of cases expressing each immune regulatory molecule in the in situ followed by invasive tumor components was: B7-H3 (94, 90), B7-H4 (82, 78), PD-L1 (6, 10), MAGE-A (39, 50), NY-ESO-1 (16, 20), B2M (100, 89), and MHC-I (78, 79). PD-L2 was negative in all cases. There was high correlation between marker expression within the in situ and invasive tumor components of the same case. B7-H4 was preferentially expressed in primary cutaneous EMPD. Co-expression of B7 family members B7-H3 and B7-H4 was found within the in situ and invasive tumor components of 74% and 48% of cases, respectively. These findings provide an initial characterization of EMPD tumor cell expression of B7-H3, B7-H4, PD-L1, PD-L2, MAGE-A, and NY-ESO-1 and indicate the potential for new immunotherapeutic options for patients with EMPD.

Immunohistochemical Detection of γ/δ T Lymphocytes in Formalin-fixed Paraffin-embedded Tissues

T lymphocytes can be distinguished based on the composition of the T-cell receptor (TCR) chain in α/β T cells and γ/δ T cells. Correspondingly, α/β lymphomas can be distinguished from γ/δ lymphomas. The latter are rare neoplasms, which are usually confined to particular organs and tissues and carry a dismal prognosis. Until recently, monoclonal antibody (mAb) clone g3.20 to the TCR γ-chain was the reagent of choice for the immunohistochemical detection of γ/δ T cells and lymphomas in standard formalin-fixed paraffin-embedded tissues. However, due to technical problems, mAb g3.20 became recently unavailable. Our attempts to identify another commercially available clone to the TCR γ-chain were unsuccessful. However, we were able to identify a mAb (clone H-41, SC-100289; Santa Cruz, Dallas, TX) to the TCR δ-chain. H-41 works well in immunohistochemistry on paraffin-embedded tissue and comparison with previously stained cases, shows superior immunolabeling to mAb g3.20. H-41 to the TCR δ-chain appears to be a suitable reagent for the replacement of mAb g3.20.

Reflectance confocal microscopy and dermoscopy aid in evaluating repigmentation within or adjacent to lentigo maligna melanoma surgical scars

BACKGROUND

Determining whether repigmentation within or adjacent to lentigo maligna or lentigo maligna melanoma (LM/LMM) scars represents recurrence of melanoma is challenging. The use of reflectance confocal microscopy (RCM) and dermoscopy may aid in differentiating true melanoma recurrence from other causes of repigmentation.

OBJECTIVES

To describe the characteristics of repigmentation within or adjacent to LM/LMM scars observable on RCM and dermoscopy.

METHODS

We retrospectively analysed patients who presented with new pigmentation within or adjacent to scars from surgically treated LM/LMM between January 2014 and December 2018. Clinical and demographic characteristics and time to recurrence were recorded. RCM was used to evaluate areas of pigmentation before biopsy. If available, dermoscopic images were also evaluated.

RESULTS

In total, 30 confocal studies in 29 patients were included in the study cohort. Twenty-one patients had biopsy-confirmed recurrent LM/LMM; the remainder had pigmented actinic keratosis (n = 4) or hyperpigmentation/solar lentigo (n = 5). RCM had sensitivity of 95.24% (95% CI, 76.18-99.88%), specificity of 77.7% (95% CI, 39.99-97.19%), positive predictive value of 90.91% (95% CI, 74.58-97.15%) and negative predictive value of 87.5% (95% CI, 50.04-98.0%). The most common dermoscopic feature observed among patients with recurrent LM/LMM was focal homogeneous or structureless areas of light-brown pigmentation (92.8% vs. 37.5% in patients with other diagnoses; P = 0.009). LM-specific dermoscopic criteria were present in only 28.5% of patients with recurrent LM/LMM.

CONCLUSIONS

Reflectance confocal microscopy and dermoscopy are valuable tools for the comprehensive evaluation of repigmentation within or adjacent to LM scars.

Clinical-grade computational pathology using weakly supervised deep learning on whole slide images

The development of decision support systems for pathology and their deployment in clinical practice have been hindered by the need for large manually annotated datasets. To overcome this problem, we present a multiple instance learning-based deep learning system that uses only the reported diagnoses as labels for training, thereby avoiding expensive and time-consuming pixel-wise manual annotations. We evaluated this framework at scale on a dataset of 44,732 whole slide images from 15,187 patients without any form of data curation. Tests on prostate cancer, basal cell carcinoma and breast cancer metastases to axillary lymph nodes resulted in areas under the curve above 0.98 for all cancer types. Its clinical application would allow pathologists to exclude 65-75% of slides while retaining 100% sensitivity. Our results show that this system has the ability to train accurate classification models at unprecedented scale, laying the foundation for the deployment of computational decision support systems in clinical practice.

BAP1-deficient tumor/nevus with germline aberration: A potential pitfall in assessing melanocytic neoplasms with single nucleotide polymorphism array

BRCA1-associated protein 1 (BAP1) is a tumor suppressor gene, located on chromosome 3p21, encoding BAP1 nuclear protein, which is associated with a subset of melanocytic tumors with distinct cytologic features. Single nucleotide polymorphism array (SNP-array) is a molecular karyotyping technique that can detect copy number variations and loss of heterozygosity in various fresh and formalin-fixed paraffin-embedded tissues. Herein we present a 56-year-old female, who presented with a lesion on her left nose/cheek that was growing in size and changing in color. Histopathology was characteristic of a BAP1-deficient melanocytic neoplasm, with a biphasic population of cytologically bland conventional nevomelanocytes and a proliferation of large epithelioid melanocytes with abundant eosinophilic cytoplasm. Immunohistochemistry for BAP1 showed loss of nuclear labeling in the epithelioid melanocytes. SNP-array revealed a chromosome 21q22.1 monoaberration with no chromosome 3 abnormalities. The detection of this aberration prompted a discussion as to whether the lesion was best designated as a nevus or tumor. SNP-array on the patient's blood showed the same monoaberration of chromosome 21q22.1. This case emphasizes the importance of interpreting microarray results in the context of morphology, as germline aberrations can be a pitfall when assessing the genomic stability of a melanocytic proliferation by SNP array.

Massively parallel sequencing analysis of benign melanocytic naevi

AIMS

Melanocytic naevi are benign lesions of the skin or mucosa that may constitute non-obligate precursors of malignant melanoma, particularly when they show lentiginous and dysplastic features. The aim of this study was to investigate the repertoire of somatic genetic alterations in melanocytic naevi.

METHODS AND RESULTS

DNA extracted from 12 melanocytic naevi and DNA from matching normal tissue were separately microdissected and subjected to targeted massively parallel sequencing of ≥300 cancer genes. A median of 5.5 (range 1-12) non-synonymous somatic mutations were detected, with 10 cases harbouring mutually exclusive BRAF V600E (6/12) or NRAS (4/12) clonal hotspot mutations. One of the two cases lacking BRAF and NRAS mutations was a dysplastic naevus harbouring an HRAS Q61L hotspot mutation. Analysis of the laser-capture microdissected components of a naevus synchronously diagnosed with in-situ and invasive malignant melanoma revealed a truncal, clonal BRAF V600E mutation, and the acquisition of a CDKN2A homozygous deletion in the invasive component, in conjunction with additional clonal mutations affecting NF2, FAT4 and KDR in both in-situ and invasive malignant components.

CONCLUSION

Melanocytic naevi harbour recurrent BRAF V600E or NRAS hotspot mutations with low mutational burdens. Our findings also show that progression from naevi to malignant melanoma may be driven by the acquisition of additional genetic alterations, including CDKN2A homozygous deletions.

Therapeutic implications of a novel driver classification system for cutaneous and unknown primary melanomas

9539

Background: Cutaneous and “unknown primary” melanomas frequently harbor alterations that activate the Mitogen Activated Protein Kinase (MAPK) pathway, and are often classified as BRAF, NRAS, NF1 mutant, or “triple wild type.” Multigene sequencing may identify additional oncogenic drivers, but the clinical impact of this information is unknown. Methods: Patients with BRAF inhibitor naïve melanoma underwent prospective tumor molecular profiling using a targeted capture-based assay (MSK-IMPACT), and demographic and treatment data were collected. Time to treatment failure was assessed for patients who received frontline PD-1 monotherapy or nivolumab plus ipilimumab. Results: 576 patients were successfully sequenced. 533 samples (96%) harbored a known or presumed oncogenic mutation in 1 of 28 genes in the RTK-RAS-MAPK pathway. 187 tumors (32%) had two or more drivers in this pathway, and the rates of driver co-alterations varied widely by specific driver. A hierarchical classification of 9 driver groups (BRAF V600E; V600K/R/M; BRAF non-V600; NRAS Q61; Other RAS; NF1; KIT; Other driver; Unknown driver) was significantly associated with tumor mutational burden, primary melanoma site, and patient age. Time to treatment failure varied by driver class and site of primary melanoma for PD-1 monotherapy but not nivolumab plus ipilimumab. 150 patients with BRAF V600 wild-type melanoma required systemic therapy after progression on checkpoint blockade. 21 were given genomically matched therapy, and 5/21 had clinical benefit for ≥6 months. Complete and durable responses were observed with TRK and ROS1 inhibitors in patients with NTRK1/2/3 and ROS1 fusion positive tumors. Conclusions: Oncogenic alterations in the RTK-RAS-MAPK pathway can be detected using targeted capture NGS in the vast majority of cutaneous and unknown primary melanomas. A hierarchical classification of 9 driver groups revealed clinically relevant melanoma subsets with varying clinical outcomes to PD-1 monotherapy. Select patients with oncogenic kinase fusions can achieve durable therapeutic benefit with targeted inhibitors of these rare drivers.