Prospective validation of the prognostic 31-gene expression profiling test in primary cutaneous melanoma.

BACKGROUND: Gene expression profiling (GEP) has been integrated into cancer treatment decision-making in multiple neoplasms. We prospectively evaluated the prognostic utility of the 31-GEP test (DecisionDx-Melanoma, Castle Biosciences, Inc) in cutaneous melanoma (CM) patients undergoing sentinel node biopsy (SNB). METHODS: One hundred fifty-nine patients (age 26-88) diagnosed with melanoma between 01/2013 and 8/2015 underwent SNB and concurrent GEP testing. GEP results were reported as low-risk Class 1 (subclasses 1A and 1B) or high-risk Class 2 (subclasses 2A and 2B). Statistical analyses were performed with chi-square analysis, t tests, log-rank tests, and Cox proportional hazard models. Recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) were estimated using Kaplan-Meier method. RESULTS: Median follow-up was 44.9 months for event-free cases. Median Breslow thickness was 1.4 mm (0.2-15.0 mm). There were 117 Class 1 and 42 Class 2 patients. Gender, age, Breslow thickness, ulceration, SNB positivity, and AJCC stage were significantly associated with GEP classification (P < 0.05 for all). Recurrence and distant metastasis rates were 5% and 1% for Class 1 patients compared with 55% and 36% for Class 2 patients. Sensitivities of Class 2 and SNB for recurrence were 79% and 34%, respectively. Of 10 SNB-positive/Class 2 patients, 9 recurred. By multivariate analysis, only SNB result and GEP class were statistically associated with both RFS (P = 0.008 and 0.0001) and DMFS (P = 0.019 and 0.001). CONCLUSIONS: Gene expression profiling Class 2 result and SNB positivity were independently associated with recurrence and distant metastasis in primary CM patients. GEP testing may have additive prognostic utility in initial staging work-up of these patients.

Evidence behind the use of molecular tests in melanocytic lesions and practice patterns of these tests by dermatopathologists.

BACKGROUND: The gold standard for the diagnosis of melanocytic lesions is histologic examination. However, as histologic examination can have its limitations, there are many clinical scenarios in which additional testing may be appropriate in an attempt to render a definitive diagnosis. METHODS: A literature review for three ancillary tests-comparative genomic hybridization (CGH)/single-nucleotide polymorphism (SNP) array, fluorescence in situ hybridization (FISH), and gene expression profiling by quantitative reverse transcription polymerase chain reaction (qRT-PCR)-was compiled and current use patterns were tabulated. Survey of the practice patterns of these tests by dermatopathologists was also accessed in the attendees of the American Society of Dermatopathology Annual Meeting (Chicago, 2016). RESULTS: Here we summarize the use of these molecular tests in melanocytic lesions. We found that 54.4% of the respondents surveyed utilize (or expect consultants to utilize) molecular testing of melanocytic lesions in their practice when appropriate. CONCLUSIONS: CGH/SNP arrays, FISH testing, and qRT-PCR applied to melanocytic lesions have allowed for more accurate classification. Just over half of those surveyed use molecular testing for melanocytic lesion with the majority sending their cases out for completion of the molecular test.

Microscopy of Common Nail Cosmetics.

Nail clipping specimens are commonly submitted for the microscopic evaluation of nail disease; however, there may be missing clinical history regarding nail polish or other adornments present on the nail at the time of specimen retrieval. For this study, 6 types of nail cosmetics were chosen and applied to the nail plate of a volunteer. After a period of at least 24 hours, the nail plates with adornments and a control nail plate were clipped and placed in formalin. Specimens were processed using a standard nail protocol. All of the specimens, except the sticker appliqué, survived the fixation process. The glitter nail polish was the only specimen found to be polarizable. None of the specimens that survived fixation were found to be PAS-positive. Cosmetic nail enhancements are easily differentiated from the nail plate microscopically; nail cosmetics appear as a distinct layer of inorganic material lying atop the nail plate. There were 2 main microscopic patterns noted on the specimens: those with 2 layers and those with 3 layers.

p53 Is a Helpful Marker in Distinguishing Langerhans Cell Histiocytosis From Langerhans Cell Hyperplasia.

Langerhans cell histiocytosis (LCH) is a proliferative disorder of Langerhans cells that can be challenging to distinguish histologically from Langerhans cell (LC) hyperplasia, seen in a variety of inflammatory dermatoses. Lesional cells in both entities demonstrate positive staining for CD1a and S100. Previous studies have demonstrated positive staining of fascin, CD31, and p53 in cases of LCH, but currently, no studies have compared the staining profiles of these markers between LCH and LC hyperplasia. The authors compared immunohistochemical staining profiles of LCH (n = 15) and various inflammatory dermatoses with LC hyperplasia (n = 15) using fascin, CD31, and p53. Fascin, CD31, and p53 were graded as a percentage of CD1a staining cells in the epidermis and dermis of each specimen. Fascin showed no significant differences in staining between the 2 entities. CD31 was positive in the dermal infiltrate in 40% of cases of LCH and negative in all cases of LC hyperplasia. p53 was positive in the epidermal infiltrate in 50% of cases of LCH, and positive in the dermal infiltrate in 93% of cases of LCH, whereas negative in all cases of LC hyperplasia. Fascin was not a helpful marker in distinguishing LCH from LC hyperplasia. CD31, if positive in the dermal infiltrate, is suggestive of a diagnosis of LCH, but exhibits a relatively low sensitivity for this purpose. p53 proved to be a helpful and accurate diagnostic immunohistochemical stain when distinguishing between LCH and LC hyperplasia.

Use of classic and novel immunohistochemical markers in the diagnosis of cutaneous myeloid sarcoma.

Cutaneous myeloid sarcoma is often challenging to diagnose based solely upon histopathological features. Although immunohistochemistry can aid in its diagnosis, specific markers have not been clearly identified. We evaluated the utility of immunohistochemical markers in 57 cutaneous myeloid sarcoma cases. In addition to classical markers (CD117, CD163, CD34, myeloperoxidase and lysozyme), we used CD33 and CD14, recently described markers in paraffin-embedded tissue samples, and Kruppel-like factor 4 (KLF-4), a novel monocytic marker. Our results show that lysozyme was expressed in 91%, CD33 in 60%, myeloperoxidase in 54%, CD34 in 39% and CD117 in 36% of cases. An antibody panel that included lysozyme, CD117 and CD33 identified all cases. The monocytic markers CD14, KLF-4 and CD163 were expressed in 60, 58 and 40% of all cases, respectively. CD14 and KLF-4 expression was significantly more common in cases with monocytic differentiation. CD14 is the single most sensitive and specific marker for monocytic differentiation (79 and 80%). Although KLF-4 in isolation is relatively insensitive (50 and 87%), it enhances sensitivity in detecting monocytic cutaneous myeloid sarcoma when combined with CD14. Our results indicate that in addition to classical immunohistochemical markers, targeted use of newer antibodies, including CD33, CD14 and KLF-4 is useful in the diagnosis of cutaneous myeloid sarcoma and in the detection of monocytic differentiation.

Mutations in the GGCX and ABCC6 genes in a family with pseudoxanthoma elasticum-like phenotypes.

A characteristic feature of classic pseudoxanthoma elasticum (PXE), an autosomal recessive disorder caused by mutations in the ABCC6 gene, is aberrant mineralization of connective tissues, particularly the elastic fibers. Here, we report a family with PXE-like cutaneous features in association with multiple coagulation factor deficiency, an autosomal recessive disorder associated with GGCX mutations. The proband and her sister, both with severe skin findings with extensive mineralization, were compound heterozygotes for missense mutations in the GGCX gene, which were shown to result in reduced gamma-glutamyl carboxylase activity and in undercarboxylation of matrix gla protein. The proband's mother and aunt, also manifesting with PXE-like skin changes, were heterozygous carriers of a missense mutation (p.V255M) in GGCX and a null mutation (p.R1141X) in the ABCC6 gene, suggesting digenic nature of their skin findings. Thus, reduced gamma-glutamyl carboxylase activity in individuals either compound heterozygous for a missense mutation in GGCX or with haploinsufficiency in GGCX in combination with heterozygosity for ABCC6 gene expression results in aberrant mineralization of skin leading to PXE-like phenotype. These findings expand the molecular basis of PXE-like phenotypes, and suggest a role for multiple genetic factors in pathologic tissue mineralization in general.