The diagnostic accuracy of Gram stain on formalin-fixed paraffin-embedded sections of skin tissue in the diagnosis of bacterial skin infection.

BACKGROUND AND OBJECTIVE: To evaluate the sensitivity, specificity, and likelihood ratios of Gram stain on formalin-fixed, paraffin-embedded (GS-FFPE) sections of skin in diagnosing bacterial skin infection. METHODS: We reviewed a retrospective series of skin specimens reported at our institution wherein histopathological assessment included Gram stain and fresh tissue was concurrently submitted for microscopy and culture. The clinicopathological correlation was the reference standard, whereby the presence of infection was deduced from the final diagnosis in each patient's case notes. RESULTS: Our sample included 168 cases (105 positive for infection). GS-FFPE showed a sensitivity of 0.43 (95% confidence interval 0.29, 0.57), a specificity of 0.98 (0.95, 1.01), a positive likelihood ratio of 21.50 (19.76, 23.24), and a negative likelihood ratio of 0.58 (0.41, 0.75). CONCLUSIONS: GS-FFPE has poor sensitivity, and a negative result should not be used as evidence to exclude infection. In contrast, it has excellent specificity and, unless the pretest probability of infection is very low, a positive result would make infection much more likely. The value of the GS-FFPE lies in cases where sterile tissue was not submitted for microbiological studies, or sterile tissue culture was negative, and there is at least a low-to-moderate pretest probability of infection.

Altered endosomal-lysosomal biogenesis in melanoma.

Cutaneous melanoma is the deadliest form of skin neoplasm and its high mortality rates could be averted by early accurate detection. While the detection of melanoma is currently reliant upon melanin visualisation, research into melanosome biogenesis, as a key driver of pathogenesis, has not yielded technology that can reliably distinguish between atypical benign, amelanotic and melanotic lesions. The endosomal-lysosomal system has important regulatory roles in cancer cell biology, including a specific functional role in melanosome biogenesis. Herein, the involvement of the endosomal-lysosomal system in melanoma was examined by pooled secondary analysis of existing gene expression datasets. A set of differentially expressed endosomal-lysosomal genes was identified in melanoma, which were interconnected by biological function. To illustrate the protein expression of the dysregulated genes, immunohistochemistry was performed on samples from patients with cutaneous melanoma to reveal candidate markers. This study demonstrated the dysregulation of Syntenin-1, Sortilin and Rab25 may provide a differentiating feature between cutaneous melanoma and squamous cell carcinoma, while IGF2R may indicate malignant propensity in these skin cancers.

BRAF mutation testing for patients diagnosed with stage III or stage IV melanoma: practical guidance for the Australian setting.

Targeted therapy (BRAF inhibitor plus MEK inhibitor) is now among the possible treatment options for patients with BRAF mutation-positive stage III or stage IV melanoma. This makes prompt BRAF mutation testing an important step in the management of patients diagnosed with stage III or IV melanoma; one that can help better ensure that the optimal choice of systemic treatment is initiated with minimal delay. This article offers guidance about when and how BRAF mutation testing should be conducted when patients are diagnosed with melanoma in Australia. Notably, it recommends that pathologists reflexively order BRAF mutation testing whenever a patient is found to have American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) stage III or IV melanoma (i.e., any metastatic spread beyond the primary tumour) and that patient's BRAF mutation status is hitherto unknown, even if BRAF mutation testing has not been specifically requested by the treating clinician (in Australia, Medicare-subsidised BRAFV600 mutation testing does not need to be requested by the treating clinician). When performed in centres with appropriate expertise and experience, immunohistochemistry (IHC) using the anti-BRAF V600E monoclonal antibody (VE1) can be a highly sensitive and specific means of detecting BRAFV600E mutations, and may be used as a rapid and relatively inexpensive initial screening test. However, VE1 immunostaining can be technically challenging and difficult to interpret, particularly in heavily pigmented tumours; melanomas with weak, moderate or focal BRAFV600E immunostaining should be regarded as equivocal. It must also be remembered that other activating BRAFV600 mutations (including BRAFV600K), which account for ∼10-20% of BRAFV600 mutations, are not detected with currently available IHC antibodies. For these reasons, if available and practicable, we recommend that DNA-based BRAF mutation testing always be performed, regardless of whether IHC-based testing is also conducted. Advice about tissue/specimen selection for BRAF mutation testing of patients diagnosed with stage III or IV melanoma is also offered in this article; and potential pitfalls when interpreting BRAF mutation tests are highlighted.

Radiation therapy-induced neuro-Sweet disease in a patient with oral squamous cell carcinoma.

Neurological involvement is a rare extracutanenous manifestation of Sweet's syndrome. We present a novel case of radiation therapy-induced neuro-Sweet disease in a patient receiving treatment for an oral squamous cell carcinoma.

Desmoglein 2 promotes vasculogenic mimicry in melanoma and is associated with poor clinical outcome.

Tumors can develop a blood supply not only by promoting angiogenesis but also by forming vessel-like structures directly from tumor cells, known as vasculogenic mimicry (VM). Understanding mechanisms that regulate VM is important, as these might be exploitable to inhibit tumor progression. Here, we reveal the adhesion molecule desmoglein 2 (DSG2) as a novel mediator of VM in melanoma. Analysis of patient-derived melanoma cell lines and tumor tissues, and interrogation of The Cancer Genome Atlas (TCGA) data, revealed that DSG2 is frequently overexpressed in primary and metastatic melanomas compared to normal melanocytes. Notably, this overexpression was associated with poor clinical outcome. DSG2+ melanoma cells self-organized into tube-like structures on Matrigel, indicative of VM activity, which was inhibited by DSG2 knockdown or treatment with a DSG2-blocking peptide. Mechanistic studies revealed that DSG2 regulates adhesion and cell-cell interactions during tube formation, but does not control melanoma cell viability, proliferation or motility. Finally, analysis of patient tumors revealed a correlation between DSG2 expression, VM network density and expression of VM-associated genes. These studies identify DSG2 as a key regulator of VM activity in human melanoma and suggest this molecule might be therapeutically targeted to reduce tumor blood supply and metastatic spread.

Post-transplant plasmablastic lymphoma of the skin.

Plasmablastic lymphoma (PBL) is a recently described rare variant of diffuse large B-cell lymphoma characterised by its aggressive nature and plasmacytic differentiation. It most frequently arises in the oral cavity of human immunodeficiency virus (HIV)-infected patients. However extra-oral involvement is becoming increasingly recognised, particularly in HIV-negative patients. We report a case of PBL presenting as multiple violaceous nodules and plaques on the leg of a HIV-negative patient, 13-years post-renal transplant. To date, 20 cases of PBL presenting in the skin have been reported. We review and compare the clinico-pathological features of these cases.

A critical analysis of reasons for improved survival from invasive cutaneous melanoma.

OBJECTIVE: To determine the extent to which increases in survival from melanoma are explained by changes in thickness, level, histological type, site of lesion, and sociodemographic characteristics. METHODS: Analyses of changes in survival among 9519 South Australians with melanoma reported to the State's population-based cancer registry during the 1980-2000 diagnostic period, using proportional hazards regression to adjust for thickness, level and other characteristics. RESULTS: Lower survivals applied for thicker lesions, deeper Clark levels, lesions on the trunk and scalp/neck, and for older cases and males. After adjusting for these characteristics, the relative risk (95% confidence limits) of case fatality for the 1994-2000 diagnostic period was 0.79 (0.63, 0.99), when compared with the 1980-1986 baseline. Prior to adjusting, the relative risk for these cases was 0.58 (0.47, 0.72). An unexpected finding was a secular change for deeper Clark levels within Breslow thickness categories. CONCLUSIONS: Approximately half the survival increase was not explained by changes in thickness, level, lesion site, and age and sex. Other possible contributors warranting further study include changes in ulceration, nodal or more distant site involvement, treatment gains and changes in tumour biology. The trend for deeper Clark levels within Breslow thickness categories requires independent confirmation.

Are cutaneous melanomas of specified thickness showing deeper levels of invasion at diagnosis?

Secular trends in Clark level were investigated by Breslow category for 8,432 invasive cutaneous melanomas diagnosed in South Australia in 1980-2000. More recently diagnosed lesions were found to have deeper levels. After adjusting for age at diagnosis, tumour site, histology, and thickness measured in half millimetres, the relative odds (95% confidence limits) of penetration to the reticular dermis or subcutaneous fat were 1.99 (1.59, 2.50) for the 1987-93 diagnostic period, and 2.82 (2.25, 3.54) for 1994-2000, when compared with 1980-86. After adjusting for melanoma thickness, the secular trends for deeper lesions applied to a broad cross-section of socio-demographic sub-groups, tumour sites, and histological types. While this similarity in trend would be consistent with a measurement effect, a real change cannot be ruled out and increased emphasis on earlier detection may be warranted. The prognostic implications of changes in inter-relationships between measures of thickness and level require periodic re-evaluation.