Utility of CD123 immunohistochemistry in differentiating lupus erythematosus from cutaneous T cell lymphoma.

AIMS: Histopathological overlap between lupus erythematosus and certain types of cutaneous T cell lymphoma (CTCL) is well documented. CD123+ plasmacytoid dendritic cells (PDCs) are typically increased in lupus erythematosus, but have not been well studied in CTCL. We aimed to compare CD123 immunostaining and histopathological features in these conditions. METHODS AND RESULTS: Skin biopsies of cutaneous lupus erythematosus (CLE, n = 18), lupus erythematosus panniculitis (LEP, n = 17), mycosis fungoides (MF, n = 25) and subcutaneous panniculitis-like T cell lymphoma (SPTCL, n = 9) were retrospectively reviewed and immunostained with CD123. Percentage, distribution and clustering of CD123+ cells were compared between CLE and MF and between LEP and SPTCL using χ2 and two-tailed t-tests. A higher percentage of CD123+ cells was observed in CLE than MF (P < 0.01), more frequently comprising ≥20% of the entire infiltrate (P < 0.01) and forming clusters (P < 0.01). Similarly, LEP showed a higher percentage of CD123+ cells than SPTCL (P = 0.01), more frequently comprising ≥20% of the infiltrate (P = 0.04) and forming clusters (P = 0.01). Basal vacuolar change or dyskeratosis was observed in all CLE cases and in 48% cases of MF cases (P = 0.05). Plasma cells were readily identified in 76% cases of LEP but in none of the SPTCL cases (P = 0.01). Adipocyte rimming by lymphocytes, hyaline fat necrosis and fibrinoid/grungy necrosis did not significantly differ between LEP and SPTCL. Dermal mucin also failed to distinguish between groups. CONCLUSIONS: CD123 immunostaining is helpful in differentiating CLE from MF and LEP from SPTCL, but should be interpreted in conjunction with clinicopathological features and other ancillary studies to ensure accurate diagnosis.

Superficial papular neuroma: Case series of a new entity.

BACKGROUND: Dermal neural lesions arise in various circumstances and may be difficult to classify. METHODS: We describe the clinical, histopathologic and immunophenotypic features of a series of terminally differentiated neural lesions not described previously, to our knowledge. RESULTS: Four cases from men aged 58 to 66 years were included. Some lesions reportedly bled, but no inciting trauma or prior biopsies were reported. None recurred after biopsy, with follow-up ranging from 19 to 113 months. All lesions were papular, with vertically oriented S100-positive spindled cells and nerve fibers in the papillary dermis. Slight epidermal hyperplasia, dilated superficial thin-walled vessels and minimal to mild inflammation were seen in each. Fibers were uniformly fine in 3 cases, with slightly thicker central fibers in the fourth. Three had parakeratotic scale. None were associated with dermal fibrosis or adnexal proliferation. Neurofilament stained axons in each. EMA was negative in all cases. CD34, melan-A and HMB45 were negative when performed. CONCLUSIONS: We report a small series of benign neural lesions and propose the name "superficial papular neuroma" for this distinct entity. Awareness is important to understand the clinical significance of these lesions and avoid misinterpretation that could lead to overtreatment, unnecessary work-up and increased cost.

Expression of the p40 isoform of p63 has high specificity for cutaneous sarcomatoid squamous cell carcinoma.

Cutaneous spindle cell malignancies such as sarcomatoid squamous cell carcinoma (SCC), leiomyosarcoma, desmoplastic melanoma (DM) and atypical fibroxanthoma (AFX) may be morphologically indistinguishable, yet accurate diagnosis is important for appropriate clinical management. The distinction among these entities relies on immunohistochemical evaluation for epidermal, muscle or melanocytic differentiation. Epidermal differentiation markers include cytokeratins and p63. p63 is expressed as two distinct isoforms, ΔNp63 (p40) and TAp63. p40 positivity is highly specific for pulmonary SCC and head and neck sarcomatoid SCC. We examined the utility of p40 vs. p63 immunostaining in the differentiation of a variety of cutaneous spindle cell malignancies, including sarcomatoid SCC (n = 27), AFX (n = 34) and DM (n = 10). p40 was less sensitive than p63 for detecting sarcomatoid SCC (56% and 81%, respectively). p63 and p40 were comparably specific for sarcomatoid SCC relative to AFX, with only rare weak staining of tumor cells for p63 and/or p40 in a minority of AFX cases, including one case with approximately 10% of cells staining weakly for p40. All cases of DM were negative for p40 and p63. Our results support continued use of p63 for diagnosis of cutaneous sarcomatoid SCC because of greater sensitivity relative to p40.

A Reassessment of the Impact and Significance of Social Media to Pathology.

CONTEXT.­: Social media (SM) use in pathology and medicine today is widespread, receives active advocacy, and is said to bring a host of benefits. In latter days, the harmful effects of SM have received attention, but they have yet been followed by greater encouragement of professionalized SM usage. SM use in medicine has seen adoption in parallel to its general ascendancy, even though the platforms are products with purposes misaligned with the practice of medicine. OBJECTIVE.­: To (1) characterize premises and forces that propel professional SM platform adoption and use, and (2) examine wide-ranging literature, both medical and nonmedical, that substantiates the premises and to find counteracting perspectives and evidence. DATA SOURCES.­: Review of the literature using relevant keyword searches in PubMed, Google Scholar, Dimensions, and Web of Science for articles that study/describe professional SM use in pathology and medicine. Additionally, we examined business, technology, and social sciences literature and high-quality gray literature (newspapers, books, blogs) that addressed questions in relation to the topic of professional SM adoption. CONCLUSIONS.­: We identified 6 major premises as motivators of professional SM use and highlight significant counteracting factors. We conclude that the harms of professionalized SM use have not been fully considered in the medical literature and that a change in direction and the creation of new communication platforms would be beneficial.