DiCaudo, David J.

AbstractBackgroundPrimary cutaneous B‐cell lymphoma (PCBCL) is a group of B‐cell lymphomas of the skin containing primary cutaneous follicle centre lymphoma (PCFCL) and marginal zone B‐cell lymphoma/lymphoproliferative disorder (PCMZL), which are indolent, and diffuse large B‐cell lymphoma, leg type (PCDLBCL‐LT), which is aggressive.ObjectivesTo evaluate treatment outcomes between PCBCL subtypes after treatment with rituximab and to compare the efficacy of intralesional against systemic rituximab in indolent subtypes.MethodsA search for patients diagnosed with PCBCL and treated with rituximab (systemic or intralesional) across all Mayo Clinic sites was performed, yielding 39 patients.ResultsEight patients had PCFCL (six treated intralesionally and two systemically), 11 had PCMZL (four intralesional, eight systemic with one dual‐treated) and 20 had PCDLBCL‐LT (all systemic). The average age at diagnosis was 62.1 years (SD = 15.1), with average follow‐up of 1852.6 days (SD = 1473.2). 69.2% of all patients treated with any form of rituximab experienced a complete response (100% PCFCL, 81.8% PCMZL and 50% PCDLBCL‐LT). When comparing all three subtypes, a significant difference was seen in overall treatment response (p = 0.022), and progressive disease rates (p = 0.015), but not in retreatment with rituximab (p = 0.440), time to retreatment (p = 0.757), recurrence (p = 0.907) or survival (p = 0.093). In the indolent subtypes, no difference in overall treatment response (p = 1.000), progressive disease rates (p = 1.000), recurrence (p = 0.650), rituximab retreatment (p = 0.650) or time to retreatment (p = 0.724) was observed.ConclusionsThis study suggests that rituximab, as systemic therapy and intralesional therapy, is effective in the management of PCBCL, and that intralesional therapy should be considered before more aggressive therapy in indolent disease.

Abstract The MHC class I antigen presentation pathway in melanoma cells has a well-established role in immune-mediated destruction of tumors. However, the clinical significance of the MHC class II antigen presentation pathway in melanoma cells is less clear. In antigen presenting cells, gamma-interferon-inducible lysosomal thiol reductase (GILT) is critical for MHC class II-restricted presentation of multiple melanoma antigens. While not expressed in benign melanocytes of nevi, GILT and MHC class II expression is induced in malignant melanocytes in a portion of melanoma specimens. Analysis of The Cancer Genome Atlas (TCGA) cutaneous melanoma dataset showed that high GILT mRNA expression was associated with improved overall survival. Expression of IFN-γ, TNF-α, and IL-1β was positively associated with GILT expression in the TCGA melanoma specimens. These cytokines were capable of inducing GILT expression in melanoma cells in vitro. GILT protein expression in melanocytes was induced in halo nevi, which are nevi undergoing immune-mediated regression, and is consistent with the association of GILT expression with improved survival in melanoma. To explore potential mechanisms of GILT’s association with patient outcome, we analyzed the mRNA expression pattern in the MHC class II antigen presentation pathway. In contrast to healthy skin where the MHC class II pathway was nearly uniformly expressed and intact, there was substantial variation in the MHC class II pathway of the TCGA melanoma dataset. Both an active and intact MHC class II pathway were associated with improved overall survival in melanoma. These studies support a role for GILT and the MHC class II antigen presentation pathway in melanoma outcome.

Gamma-interferon-inducible lysosomal thiol reductase (GILT) is critical for MHC class II restricted presentation of multiple melanoma antigens. There is variable GILT protein expression in malignant melanocytes in melanoma specimens. High GILT mRNA expression in melanoma specimens is associated with improved overall survival, before the advent of immune checkpoint inhibitors (ICI). However, the association of GILT in metastatic melanoma with survival in patients treated with ICI and the cell type expressing GILT associated with survival have not been determined. Using RNA sequencing datasets, high GILT mRNA expression in metastatic melanoma specimens was associated with improved progression-free and overall survival in patients treated with ICI. A clinical dataset of metastatic melanoma specimens was generated and annotated with clinical information. Positive GILT immunohistochemical staining in antigen presenting cells and melanoma cells was observed in 100% and 65% of metastatic melanoma specimens, respectively. In the subset of patients treated with ICI in the clinical dataset, high GILT protein expression within melanoma cells was associated with improved overall survival. The association of GILT mRNA and protein expression with survival was independent of cancer stage. These studies support that high GILT mRNA expression in bulk tumor samples and high GILT protein expression in melanoma cells is associated with improved survival in ICI-treated patients. These findings support further investigation of GILT as a biomarker to predict the response to ICI.

AbstractBackgroundNecrobiosis lipoidica (NL) is an uncommon granulomatous dermatosis that can occur in patients with or without associated diabetes mellitus (DM). Prior studies have attempted to determine distinctive histopathologic features of NL in patients with and without DM.MethodsA retrospective review of 97 patients with NL was performed to determine the similar and distinctive histopathologic features in patients with DM and without DM.ResultsOf the 97 patients, 32% (n = 31) had DM. Epidermal acanthosis was seen more commonly in diabetics than nondiabetics (32.3% vs. 12.1%; p = 0.017). Naked (sarcoidal/tuberculoid) granulomas were more frequently observed in nondiabetics than diabetics (22.7% vs. 3.2%; p = 0.016). Eosinophils were more common in nondiabetics than diabetics (38.5% vs. 9.7%; p = 0.004), while neutrophilic infiltration was more common in diabetics than nondiabetics (45.2% vs. 17.5%; p = 0.004).ConclusionsThis study corroborates well‐documented histopathologic features of NL and shows distinctive histopathologic features of NL among patients with DM‐I, DM‐II, and without DM. These results support the hypothesis that there are different underlying drivers of NL between diabetics and nondiabetics.

Melanoma is the sixth most common cancer in the US. Immunotherapies, such as anti‐CTLA‐4 and anti‐PD‐1, have transformed the treatment of advanced melanoma; however, a subset of patients fail to respond to immunotherapy. Thus, improved predictors of the anti‐melanoma immune response and response to immunotherapy are needed. We have previously shown that 1) gamma‐interferon‐inducible lysosomal thiol reductase (GILT) is critical for MHC class II‐restricted presentation of a melanoma antigen, 2) there is variable GILT protein expression in melanoma cells from primary and cutaneous metastatic melanoma specimens, and 3) high GILT mRNA expression in melanoma specimens is associated with improved overall survival. Here, we created a database of n = 43 metastatic melanoma patients (stage III or IV) annotated with clinical outcome. Formalin‐fixed, paraffin‐embedded sections of pre‐treatment metastatic melanoma specimens were tested for GILT protein expression using immunohistochemistry and scored by a dermatopathologist and dermatologist. GILT expression in melanoma cells was detected in 65% of lymph node and distant organ metastases, consistent with our prior finding of GILT expression in 58% of cutaneous metastases. The frequency of GILT‐staining melanoma cells was determined by the ratio of the area of tumor cells with positive GILT staining to the total area of tumor cells. The frequency of GILT‐staining melanoma cells among specimens with positive GILT staining was 15.2% ± 24.7% (mean ± SD). The median frequency of GILT staining was used to divide the patients into no/low and high GILT expression groups. The median overall survival was 52.8 months in the no/low GILT expression group, while the median overall survival was not reached in the high GILT expression group (log‐rank, p = 0.67). For the n = 34 patients who were treated with immunotherapy targeting CTLA‐4 and/or PD‐1, the median overall survival was 38.2 months in the no/low GILT expression group, while the median overall survival was not reached in the high GILT expression group (log‐rank, p = 0.83). These data suggest that high GILT expression in melanoma cells may be associated with improved overall survival, although a statistically significant association of GILT with survival was not observed in the whole group or the subset of patients treated with immunotherapy. A limitation of the current analysis is that 65% of patients have incomplete clinical outcome data. This study demonstrates variable GILT protein expression in tumor cells in metastatic melanoma specimens. Updated clinical outcome data will allow us to better evaluate the association of GILT protein expression in melanoma cells with overall survival and response to immunotherapy in metastatic melanoma patients.

AbstractMucous membrane pemphigoid (MMP) is a rare chronic immunobullous disease that involves the mucous membranes and may result in significant scarring and complications if diagnosis is delayed. MMP typically occurs in elderly patients, with very few cases reported in children. Here, we present a 12‐year‐old female patient with childhood‐onset oral and genital MMP, clinically suspected to be lichen sclerosus, but eventually diagnosed as MMP after multiple supportive biopsies and confirmatory direct immunofluorescence. Although treatment was challenging, the combined use of systemic corticosteroids, dapsone, and mycophenolate mofetil was ultimately successful in achieving disease control.

Abstract Context.—Selected cutaneous neoplasms share features with benign counterparts or have subtle morphologic features that could be overlooked by the pathologist. Objective.—To present clues to the diagnosis of potentially deceptive malignancies, including desmoplastic malignant melanoma, nevoid malignant melanoma, subcutaneous lymphoma, metastatic breast carcinoma, and epithelioid sarcoma. Data Sources.—Published literature and personal experience. Conclusions.—Knowledge of commonly misdiagnosed cutaneous neoplasms will help the general surgical pathologist avoid these potential pitfalls in neoplastic dermatopathology.