[Main Types of Cysts in Dermatopathology: Part 2]. / Principales tipos de quistes en dermatopatología: Parte 2.

This is the second article in a two-part series published in this journal, in which we examine the histopathological characteristics, as well as the differential diagnosis, of the main entities that present as cystic and pseudocystic structures in cutaneous biopsy. In this second article, we address ciliated cutaneous cysts, branchial cysts, Bartholin's cysts, omphalomesenteric cysts, thymic cysts, thyroglossal duct cysts, synovial cysts, and median raphe cysts, as well as mucocele, ganglion, and auricular and digital myxoid pseudocysts.

[Main Types of Cysts in Dermatopathology: Part 1]. / Principales tipos de quistes en dermatopatología: parte 1.

Cystic structures represent one of the most common findings in dermatopathology. These encompass both cystic tumors and pseudocysts resulting from the accumulation of certain substances, such as mucin. In a two-part series (of which this is the first part), we have reviewed the principal types of cysts and pseudocysts that may be observed in cutaneous biopsies, examining their histopathological features and primary differential diagnoses. This first part encompasses infundibular cysts, eruptive dermoid cysts, pigmented follicular cysts, pilonidal cysts, tricholemmal cysts, milium cysts, hybrid cysts, bronchogenic cysts, as well as steatocystoma, hydrocystoma, and comedones.

Pancreatic panniculitis revisited: A series of 34 patients.

BACKGROUND: Pancreatic panniculitis is a rare form of panniculitis generally associated with acute or chronic pancreatitis, and less frequently with pancreatic carcinoma. Clinically, it presents with subcutaneous nodules usually located in the lower extremities, however, it presents an almost pathognomonic histopathological finding with enzymatic fat necrosis in the adipose tissue. METHODS: In this retrospective case series of five hospitals, biopsy specimens of cutaneous lesions of pancreatic panniculitis were reviewed. Clinical information was obtained through medical records. RESULTS: A total of 34 cases were included, 23 women and 11 men, aged between 31 and 92 years. The most common associated pancreatic disease was acute pancreatitis (23 cases) and its main triggering cause was gallstones (17 cases). In two patients it was related to chronic pancreatitis and six cases were associated with malignancy. Histopathological findings were always the key to diagnosis. In the biopsies reviewed, mostly lobular panniculitis with the characteristic necrosis of the adipocytes was observed. In addition, nine of the cases presented with Splendore-Hoeppli phenomenon. CONCLUSIONS: We present the largest series of pancreatic panniculitis. Clinically, the female predominance and biliary lithiasis as the main cause of acute pancreatitis are to be emphasized. Histopathologically, a peripheral eosinophilic striated rim surrounding aggregates of ghost adipocytes consistent with Splendore-Hoeppli is an additional clue to its diagnosis.

AI-empowered cellular morphometric risk score improves prognostic stratification of cutaneous squamous cell carcinoma.

INTRODUCTION: Risk stratification of cutaneous squamous cell carcinoma (CSCC) is essential for managing patients. Artificial intelligence and machine learning might help stratify patients with CSCC by risk using more than solely clinical and histopathological factors. METHODS: A retrospective cohort of 104 CSCCs excised with clear margins was retrieved. Clinical and histopathological risk factors were evaluated. Hematoxylin and eosin-stained slides were scanned and analyzed by an algorithm based on the stacked predictive sparse decomposition technique. Cellular morphometric biomarkers (CMBs) were identified via machine learning and used to derive a cellular morphometric risk score (CMRS) that classified CSCC into clusters of differential prognosis. Concordance analysis, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated and compared with results obtained with the Brigham and Women's Hospital (BWH) staging system. The performance of the combination of the BWH staging system and the CMBs was also analyzed. RESULTS: There were no differences among CMRS groups in terms of clinical and histopathological risk factors and T-stage assignment, but there were significant differences in prognosis. Combining the CMRS with BWH staging systems increased distinctiveness and improved prognostic performance. C-indices were 0.92 for local recurrence and 0.91 for nodal metastasis when combining the two approaches. The NPV was 94.41% and 96.00%, the PPV was 36.36% and 41.67%, and accuracy reached 86.75% and 89.16% with the combined approach. CONCLUSION: CMRS is helpful for CSCC risk stratification beyond classic clinical and histopathological risk features. Combining the information from the CMRS and the BWH staging system offers outstanding prognostic performance for high-risk CSCC patients.

Primary Cutaneous Marginal Zone Lymphoproliferative Disorder of Donor Origin after Allogeneic Hematopoietic Stem Cell Transplantation.

ABSTRACT: Primary cutaneous posttransplant lymphoproliferative disorders (PTLDs) after allogeneic hematopoietic stem cell transplant (allo-HSCT) are exceedingly rare, with only 6 published cases, all of them consisting in T-cell neoplasms. In this report, we present for the first time a donor-derived B-cell PTLD consisting in a primary, cutaneous, B-cell, marginal zone, lymphoproliferative disorder (PCMZLPD). The patient, a 37-year-old woman with a history of Hodgkin lymphoma received an allo-HSCT from her healthy, matched, related father, achieving complete host chimerism in the bone marrow and peripheral blood. However, 8 years after the allo-HSCT, she presented asymptomatic skin lesions consisting in oval, well-defined, slightly raised erythematous plaques, located on the arms, trunk, and legs. Skin biopsies of 2 lesions demonstrated a class-switched IgG+, EBV-, PCMZLPD, showing kappa light chain restriction and monoclonal rearrangement of the IgH gene. Microsatellite genotyping and 2-color fluorescence in situ hybridization (X and Y chromosomes) confirmed that the origin of the neoplastic cells was the donor graft. The lesions showed an indolent behavior, good response to topical corticosteroids, and no need for systemic treatment. Our case broadens the spectrum of PTLD, a diverse group of lymphoid and/or plasmacytic proliferations with variable clinical presentations and histopathological features.

High-risk mucosal human papillomavirus-associated squamous cell carcinoma of the fingers presents distinctive clinicopathological characteristics and outcomes: a bicentric retrospective study.

BACKGROUND: High-risk mucosal human papillomavirus (HR-HPV) seems to play a role in cutaneous squamous cell carcinoma (cSCC), particularly in nail tumours, where genitodigital transmission has been suggested. The role of HR-HPV in nonungual cSCC of the finger needs to be clarified. AIM: To evaluate the prevalence, clinicopathological characteristics, surrogates and outcomes of HR-HPV in cSCC of the finger. METHODS: This was an observational bicentric study including patients with an excised in situ or invasive cSCC located on the finger. Differences in HR-HPV and non-HR-HPV tumours were evaluated. RESULTS: Forty-five patients (45 tumours) were included. HR-HPV was detected in 33% of cases (22% HPV type 16). The mean age was lower in patients with HR-HPV than in those with non-HR-HPV (62·4 vs. 81·1 years, P = 0·001). HR-HPV tumours were smaller (10 mm vs. 15 mm, P = 0·07) and more frequently intraepidermal (60% vs. 20%, P = 0·004). The absence of elastosis (P = 0·030) and inflammation (P = 0·026) and the presence of basaloid morphology (P = 0·003) were surrogates of HR-HPV detection. Mean p16 positivity was 61% in HR-HPV and 36% in non-HR-HPV tumours (P = 0·061). Recurrence after surgery was more common in HR-HPV tumours (58% vs. 34%), although this was not statistically significant. HR-HPV was detected in 27% of the nonungual tumours. CONCLUSION: HR-HPV-associated cSCC of the finger appears in younger patients, is smaller and is less infiltrative than non-HR-HPV tumours. The presence of a basaloid morphology and the absence of elastosis and inflammation could be used as markers for HR-HPV detection. The high prevalence of HR-HPV in nonungual cSCC suggests its aetiopathogenic role in these tumours.

Clinical and histopathological evaluation of 50 acantholytic cutaneous squamous cell carcinomas: Analysis outcome in a retrospective case-control study.

BACKGROUND: Acantholytic cutaneous squamous cell carcinomas (aCSCCs) have been classically considered as a high-risk variant of CSCC. However, more recent studies show that aCSCC does not confer more aggressiveness. This study aims to establish whether the prognosis of the aCSCC is worse than that of the non-acantholytic (naCSCC) or not. METHODS: Retrospective case-control study with 50 aCSCCs and 50 naCSCCs. For each aCSCC, an naCSCC with similar high-risk features to the aCSCC but with no acantholysis was selected. Prognosis between both groups was compared. RESULTS: The mean age was 86 years (SD 9.61). Sixty-one patients were men. Thirty-nine CSCCs were located in high-risk head and neck areas. Twenty CSCCs exhibited a poor degree of differentiation, and 36 showed an infiltrative growth pattern. The tumor diameter was 18.71 mm (interquartile range, IQR 35), and the tumor thickness was 6.72 mm (IQR 15.50). Twelve CSCCs exhibited perineural infiltration, and eight CSCCs exhibited invasion beyond the subcutaneous fat. Positive margins after excision of the tumor in 22 aCSCCs vs eight naCSCCs (P < 0.02). Nineteen poor-prognosis events were observed (local recurrence, lymph node metastasis, and death from CSCC). However, no differences were observed between both groups when comparing poor-prognosis events. CONCLUSION: The proportion of unfavorable events is similar in aCSCC and naCSCC. The acantholytic histopathological subtype is not associated with a poorer prognosis than the non-acantholytic CSCC in our cohort.

Clinical and pathological features of Merkel cell carcinoma: A 4-year follow-up observational retrospective study in Spain.

BACKGROUND: Merkel cell carcinoma (MCC) is a malignant skin cancer with a 5-year survival rate of approximately 50%. Knowledge of MCC has increased in recent years mostly due to improved diagnosis techniques. In Spain there is lack of information regarding the incidence and tumour characteristics, and the treatment approaches are not standardised. The objective of this study was to provide information of the clinical and epidemiological characteristics of MCC patients in Spain. METHODS: Retrospective, observational study involving 192 patients from 25 Spanish hospitals. Evaluated variables included overall survival and incidence rate of Merkel cell polyomavirus, in patients diagnosed from 2012 to 2016. RESULTS: The Spanish incidence rate was estimated 0.32/100,000 inhabitants/year, with variations according to geographical regions, being slightly higher in areas with greater sunlight exposure. In total, 61.5% of tumours showed expansive growth (progressive growth of the tumour), 78.6% showed localisation in UV-exposed skin. 97.4% of patients were diagnosed by excisional biopsy. Surgery was the first line treatment in 96.6% of patients, radiotherapy in 24.6%, and chemotherapy in 6.3%. These treatments were not mutually exclusive. Median overall survival was 38.3 months (78.4% at 12 months and 60% at 24 months). MCPyV was present in 33.8% of patients. CONCLUSION: The incidence of MCC in Spain is one of the highest in Europe, with a slight predominance in men. The sample has shown that a biopsy is available for diagnosis in most cases. Moreover, the treatment is surgical when the tumour is localized and is associated with lymphadenectomy, and/or it is radiotherapy if widespread.

TERT promoter mutation in sebaceous neoplasms.

TERT promoter (TERTp) mutations widely occur in multiple human neoplasms, and they have been related to different clinicopathological features. To date, this mutation has not been identified in sebaceous tumors. Here, we analyzed TERTp mutations in 91 sebaceous neoplasms (17 adenomas, 45 sebaceomas, and 29 carcinomas). We detected mutations in 26.7% (8 of 29) of sebaceous carcinomas by pyrosequencing and Sanger sequencing. No mutation was detected in adenomas or sebaceomas. The difference was significant between sebaceoma and carcinoma. The most frequent TERTp mutations were C228T and C250T in 37.5% (3 of 8) of mutated cases each one. The mutation was not associated with poor clinical evolution. Using NGS, 20 of 29 (68.5%) sebaceous carcinomas harbored mutations in 8 of the 30 genes analyzed (TP53, TERTp, EGFR, ATRX, PDGFRA, CDKN2A, PTEN, and ACVR1). With immunohistochemistry, only 1 of 8 (12.5%) TERTp-mutated carcinomas lacked mismatch repair (MMR) protein expression compared to 6 of 21 (31.6%) of non-mutated ones. Sebaceous carcinomas with MMR protein expression had significantly higher frequency of total mutations and TP53 and TERTp mutations than MMR protein-deficient carcinomas. In conclusion, TERTp mutation has been detected in sebaceous carcinomas, and its presence could be useful to differentiate sebaceous carcinoma from sebaceoma, a difficult histopathological challenge.

Protocolo de diagnóstico histológico para muestras de pacientes con melanoma cutáneo. Documento de consenso de la SEAP y la AEDV para el Registro Nacional de Melanoma / Protocol for the histologic diagnosis of cutaneous melanoma: consensus statement of the Spanish Society of Pathology and the Spanish Academy of Dermatology and Venereology (AEDV) for the National Cutaneous Melanoma Registry

El presente texto es una propuesta de protocolo de diagnóstico histológico para el melanoma cutáneo realizada a instancias del Registro Nacional de Melanoma de la Academia Española de Dermatología y Venereología. Tras una búsqueda bibliográfica, un grupo de ocho panelistas (siete patólogos) decidieron entre 36 variables del tumor primario, el ganglio centinela y la linfadenectomía incluir un total de 30 variables mediante el método de Delphi modificado. Se han consensuado las variables que deberían contener un informe histológico de melanoma cutáneo para que puedan ser utilizadas en el Registro de Melanoma o servir de modelo para los distintos Servicios de Anatomía Patológica a la hora de elaborar sus propios informes de forma rutinaria

This article describes a proposed protocol for the histologic diagnosis of cutaneous melanoma developed for the National Cutaneous Melanoma Registry managed by the Spanish Academy of Dermatology and Venereology (AEDV). Following a review of the literature, 36 variables relating to primary tumors, sentinel lymph nodes, and lymph node dissection were evaluated using the modified Delphi method by a panel of 8 specialists (including 7 pathologists). Consensus was reached on the 30 variables that should be included in all pathology reports for cutaneous melanoma and submitted to the Melanoma Registry. This list can also serve as a model to guide routine reporting in pathology departments

Spectrum of Clinicopathologic Findings in COVID-19-induced Skin Lesions: Demonstration of Direct Viral Infection of the Endothelial Cells.

The novel coronavirus disease (COVID-19) is a rapidly spreading pandemic, secondary to severe acute respiratory syndrome coronavirus 2. The severity and the little knowledge that we have of the disease have made us focus mostly on the respiratory symptoms. As we bend the curve, other findings reported in association with COVID-19 become of importance for specialists to recognize. We describe the spectrum of clinicopathologic lesions in the skin that can be the only symptom or the first manifestation of COVID-19 and demonstrate the origin of the virus. We collected 25 patients with skin lesions in this context. We recognized 5 types of cutaneous manifestations including acute acroischemic or chilblain-like lesions (11), purpura palpable (2), exanthemas (9), urticarial eruptions (1), and other lesions (2) that might appear with more unspecific pictures. Chilblain-like lesions were the most common form of presentation, which tend to appear as self-healing, erythematous-necrotic plaques mostly on the feet, in young patients with no systemic symptoms associated. Importantly, we visualized viral particles with electron microscopy in 5 of 13 cases analyzed. In this study, we seek to draw a picture of the spectrum of clinicopathologic lesions that may appear in the skin in the context of COVID-19. Although apparently skin lesions are not correlated with disease severity, it may help in some cases to recognize and control the spread of the infection sooner.

[Protocol for the histologic diagnosis of cutaneous melanoma: consensus statement of the Spanish Society of Pathology and the Spanish Academy of Dermatology and Venereology (AEDV) for the National Cutaneous Melanoma Registry]. / Protocolo de diagnóstico histológico para muestras de pacientes con melanoma cutáneo. Documento de consenso de la SEAP y la AEDV para el Registro Nacional de Melanoma.

This article describes a proposed protocol for the histologic diagnosis of cutaneous melanoma developed for the National Cutaneous Melanoma Registry managed by the Spanish Academy of Dermatology and Venereology (AEDV). Following a review of the literature, 36 variables relating to primary tumors, sentinel lymph nodes, and lymph node dissection were evaluated using the modified Delphi method by a panel of 8 specialists (including 7 pathologists). Consensus was reached on the 30 variables that should be included in all pathology reports for cutaneous melanoma and submitted to the Melanoma Registry. This list can also serve as a model to guide routine reporting in pathology departments.

Value of PD-L1, PD-1, and CTLA-4 Expression in the Clinical Practice as Predictors of Response to Nivolumab and Ipilimumab in Monotherapy in Patients With Advanced Stage Melanoma.

BACKGROUND: The introduction of immune checkpoint inhibitors (ICI) has improved the survival outcomes of patients with advanced melanoma. To date, only a few studies have evaluated the immunohistochemical (IHC) expression of PD-1 and CTLA-4 in tumor-infiltrating lymphocytes (TILs) as predictive markers of response to ICI, most of them in the context of clinical trials. Moreover, the predictive value of PD-L1 in melanoma cells in the response to immunotherapy is unclear. The aim of our study was to assess the IHC expression of PD-L1, PD-1, and CTLA-4 in samples of patients with advanced melanoma and to establish their prognostic value as predictors of ICI response in a university hospital. METHODS: The expression of PD-L1, PD-1, and CTLA-4 was evaluated in pretreatment tumor samples in a series of 35 patients, 21 patients treated with nivolumab and 14 patients with ipilimumab in monotherapy. RESULTS: In the nivolumab group, 4 tumors (19%) were positive for PD-L1 and all of them showed a partial response to the treatment. However, 4 patients whose tumors did not express PD-L1 also responded to nivolumab. PD-1 expression was not associated with better progression-free survival (PFS). In the ipilimumab group, 5 patients (35.7%) showed expression of CTLA-4. Positive cases showed a better PFS; however, one negative case responded to ipilimumab. CONCLUSIONS: Nivolumab produces a better response compared with ipilimumab in patients with melanoma. The IHC expression of PD-L1 and CTLA-4 are associated with a higher response rate to nivolumab and ipilimumab, respectively, and better PFS, but the existence of responder patients with negative expression suggests that they are not adequate biomarkers to select candidate patients for ICI in the clinical practice.