[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.

Combined Merkel Cell Carcinoma and Squamous Cell Carcinoma: A Systematic Review.

Combined Merkel cell carcinoma (MCC) and squamous cell carcinoma (SCC) have classically been regarded as more aggressive than conventional, pure, Merkel cell polyomavirus (MCPyV)-positive MCC. It is still unknown whether combined MCC and SCC are more aggressive than pure, MCPyV-negative MCC, and the origin of both the SCC and MCC elements of these combined tumors has not been elucidated. The main objective of this systematic review was to assess whether combined MCC and SCC tumors are associated with a worse prognosis than pure MCC; the secondary goals were the characterization of the clinical and histopathological features of these combined neoplasms. A total of 38 studies, including 152 patients, were selected for review. In total, 76% of the cases were MCPyV-negative, whereas 4% were MCPyV-positive. The most frequent histopathological pattern was that of an SCC in situ combined with a dermal MCC (36%), followed by both an in situ and invasive SCC combined with a dermal MCC (20%). Forty-seven percent of all cases fitted in the morphology of the so-called "collision tumors". Three combined MCC cases that would fit in the morphological category of collision tumors presented both squamous and neuroendocrine elements in their respective nodal metastases. The mean overall survival was 36 months, comparable to that of pure, MCPyV-negative MCC. This review found similarly aggressive behavior for combined MCC and SCC and pure, MCPyV-negative MCC. Preliminary data strongly suggest that all MCPyV-negative MCC tumors, whether combined or pure, are part of a common spectrum.

Topical Imiquimod in Primary Cutaneous Extramammary Paget's Disease: A Systematic Review.

Extramammary Paget's disease (EMPD) is subclinical in extent and multifocal in nature. There is no global consensus for treatment, so its management represents a challenge in clinical practice. Therefore, we conducted a systematic review through the main electronic databases to assess the effectiveness of topical imiquimod in cutaneous EMPD and to discuss its management. Finally, 24 studies involving a total of 233 EMPD patients treated with topical imiquimod were selected. The topical imiquimod response rate was 67%, and the complete response (CR) rate was 48%. Patients were treated with a three-four times a week regimen in most cases, ranging between 2 to 52 weeks. In addition, imiquimod was applied as an adjunctive treatment in 21 patients, achieving a CR rate of 71%. Consequently, imiquimod therapy could achieve a good response ratio as a first-line treatment, as adjuvant and neo-adjuvant therapy, and as a treatment for recurrent disease. The heterogeneity between studies and the lack of a control arm made it impossible to conduct a meta-analysis. To improve the quality of evidence on EMPD, multicenter studies are essential to collect a larger number of patients and, consequently, obtain high-quality evidence to standardize treatment. The Prospero registration number is CRD42023447443.

Prognostic factors for satellitosis or in-transit metastasis in cutaneous squamous cell carcinoma: A multicentric cohort study.

BACKGROUND: Satellitosis or in-transit metastasis (S-ITM) has clinical outcomes comparable to node-positivity in cutaneous squamous cell carcinoma (cSCC). There is a need to stratify the risk groups. OBJECTIVE: To determine which prognostic factors of S-ITM confer an increased risk of relapse and cSCC-specific-death. METHODS: A retrospective, multicenter cohort study. Patients with cSCC developing S-ITM were included. Multivariate competing risk analysis evaluated which factors were associated with relapse and specific death. RESULTS: Of a total of 111 patients with cSCC and S-ITM, 86 patients were included for analysis. An S-ITM size of ≥20 mm, >5 S-ITM lesions, and a primary tumor deep invasion was associated with an increased cumulative incidence of relapse (subhazard ratio [SHR]: 2.89 [95% CI, 1.44-5.83; P = .003], 2.32 [95% CI, 1.13-4.77; P = .021], and 2.863 [95% CI, 1.25-6.55; P = .013]), respectively. Several >5 S-ITM lesions were also associated with an increased probability of specific death (SHR: 3.48 [95% CI, 1.18-10.2; P = .023]). LIMITATIONS: Retrospective study and heterogeneity of treatments. CONCLUSION: The size and the number of S-ITM lesions confer an increased risk of relapse and the number of S-ITM an increased risk of specific-death in patients with cSCC presenting with S-ITM. These results provide new prognostic information and can be considered in the staging guidelines.

Superficial GLI1-amplified mesenchymal neoplasms: Expanding the spectrum of an emerging entity which reaches the realm of dermatopathology.

Mesenchymal neoplasms with GLI1 alterations (rearrangements and/or amplification) have been reported recently in several anatomic locations, which include head and neck, soft tissue, and gastrointestinal tract. Herein, to the best of our knowledge, we describe the first three cases of superficial/subcutaneous mesenchymal neoplasm with GLI1 amplification. The neoplasms exhibited low-grade cytologic features with predominant round cell morphology, glomangioma-like areas and a rich background capillary network. There were two to three mitotic figures per 10 HPF and focal necrosis in one case. The tumors exhibited variable expression of CDK4, MDM2, STAT6, D2-40, CD56 and cyclin D1. p16 had strong and diffuse nuclear and cytoplasmic expression in two cases. Numerous other stains were negative. Fluorescence in situ hybridization detected GLI1, DDIT3, and CDK4 coamplification in all cases, while next generation sequencing did not detect a GLI1 gene fusion. The overall features were compatible with a GLI1-amplified mesenchymal neoplasm. In Case 1 a new distant skin lesion appeared 1 month after the surgery exhibiting similar morphology albeit with a higher mitotic index. In Cases 2 and 3, there is no evidence of local recurrence or systemic disease after 8 years and 1 month of follow-up, respectively. These new cases of superficial GLI1-amplified neoplasm expand its clinical spectrum and enter the realm of dermatopathology. The combination of CDK4, cyclin D1, D2-40, and p16 expression with variable MDM2, STAT6, CD56, and S100 immunoreactivity in a low-grade neoplasm with round/ovoid cytomorphology resembling a vascular or adnexal neoplasm may suggest the possibility of GLI1-amplified neoplasm.

Cutaneous Ossifying Amyloidoma.

ABSTRACT: Amyloidoma, otherwise known as tumoral amyloidosis, is a localized deposition of amyloid (AL-type or AA type) without systemic amyloidosis. It is the rarest form of tissue amyloid deposition, and up to 7% of amyloidomas develop systemic amyloidosis.Cutaneous AL-type amyloidoma is considered by many authors as an unusual variant of primary cutaneous marginal zone lymphoma. Although cutaneous amyloidoma can form calcifications, ossification is extremely unusual, with only 1 case previously published to date.We report the case of a 75-year-old woman with voluminous and strikingly ossifying AL-type amyloidoma in the left pretibial skin. Her medical history included excision of hepatic hydatidic cysts 25 years prior and diffuse large B-cell lymphoma of the left parotid gland 8 years prior treated with chemotherapy and radiotherapy with complete response. After the diagnosis of amyloidoma, an extension study with cervical, chest, abdominal, and pelvic TC was performed, with no additional lesions found. Serum and protein electrophoresis revealed elevations in kappa light chain and IgA immunoglobulin levels but did not reveal monoclonal bands. In situ hybridization for immunoglobulin light chains showed monotypic kappa expression in plasma cells infiltrating the amyloidoma.Extensive ossification in amyloidomas can make diagnosis difficult; therefore, we describe an interesting case of this histopathologically peculiar amyloidoma.

Activity and safety of topical pimecrolimus in patients with early stage mycosis fungoides (PimTo-MF): a single-arm, multicentre, phase 2 trial.

BACKGROUND: The calcineurin pathway is often activated in mycosis fungoides. We aimed to assess the activity and safety of topical pimecrolimus, a calcineurin inhibitor, in patients with early mycosis fungoides. METHODS: PimTo-MF was a single-arm, multicentre, phase 2 trial done at six medical centres in Spain. Patients (aged ≥18 years) had histologically confirmed early mycosis fungoides (stages IA-IIA) and an Eastern Cooperative Oncology Group performance status of 0-1. Key exclusion criteria included the use of concurrent treatments for mycosis fungoides, including sunbathing, topical or systemic corticosteroids, and other calcineurin inhibitors. Patients applied topical pimecrolimus 1% cream on their skin lesions twice daily for 16 weeks (1 g per 2% of body surface), with subsequent follow-up of 12 months. Dosage modifications were not allowed. To evaluate adherence to the treatment, patients were instructed to return all empty tubes to the hospital (as per drug accountability protocols). The primary endpoint was the overall response ratein the intention-to-treat population. PimTo-MF is registered with EudraCT, 2014-001377-14, and is complete. FINDINGS: Between March 1, 2015, and Sept 30, 2016, 39 patients were enrolled. All patients were assessable, with a median age of 51·5 years (IQR 45-62), and the population was predominantly male (24 male [62%], 15 female [38%]). Median follow-up after baseline was 5·7 years (IQR 5·7-6·2). 22 (56%) of 39 patients had an overall response (one complete response, 21 partial responses). Responses were observed across IA (14 [54%] of 26 patients) and IB (eight [73%] of 11 patients) clinical stages, but not IIA. Topical pimecrolimus was well tolerated and no patient required a dose reduction or discontinued treatment because of unacceptable drug-related toxicity. No patients were lost to follow-up or discontinued treatment. 13 (33%) of 39 patients reported adverse events; transitory mild burning or pruritus (grade 1) was the most common, seen in eight (21%) patients. In three (8%) of these patients, the burning or pruritus was considered related to treatment. No grade 4 or 5 adverse events were observed. INTERPRETATION: Pimecrolimus 1% cream seems active and safe in patients with early stage mycosis fungoides. Our findings should be taken with caution until long-term follow-up data are obtained that confirm the safety of this treatment. Further controlled clinical trials are warranted to confirm these results. FUNDING: Instituto de Salud Carlos III and the European Regional Development Fund. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section.

Update on Management Recommendations for Advanced Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer, the incidence of which has risen over the last years. Although cSCC rarely metastasizes, early detection and treatment of primary tumours are critical to limit progression and local invasion. Several prognostic factors related to patients' clinicopathologic profile and tumour features have been identified as high-risk markers and included in the stratification scales, but their association with regional control or survival is uncertain. Therefore, decision-making on the diagnosis and management of cSCC should be made based on each individual patient's characteristics. Recent advances in non-invasive imaging techniques and molecular testing have enhanced clinical diagnostic accuracy. Surgical excision is the mainstay of local treatment, whereas radiotherapy (RT) is recommended for patients with inoperable disease or in specific circumstances. Novel systemic treatments including immunotherapies and targeted therapies have changed the therapeutic landscape for cSCC. The anti-PD-1 agent cemiplimab is currently the only FDA/EMA-approved first-line therapy for patients with locally advanced or metastatic cSCC who are not candidates for curative surgery or RT. Given the likelihood of recurrence and the increased risk of developing multiple cSCC, close follow-up should be performed during the first years of treatment and continued long-term surveillance is warranted.

Determination of Margins for Tumor Clearance in Dermatofibrosarcoma Protuberans: A Single-Center Study of 222 Cases Treated With Modified Mohs Surgery.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is an invasive skin tumor traditionally associated with very high recurrence rates when treated with conventional surgery (CS). OBJECTIVE: To calculate the minimum margin that would have been required to achieve complete tumor clearance with hypothetical CS. To analyze DFSP characteristics and Mohs micrographic surgery (MMS) effectiveness in treatment of this tumor. MATERIALS AND METHODS: Minimum margin was calculated by measuring the largest distance from the visible edge of the tumor to the edge of the surgical defect. Tumor variables (age, sex, size, time since onset, and location) were correlated with surgical variables (number of stages and minimum margin). RESULTS: We studied 222 cases of DFSP treated with MMS. A mean of 1.47 MMS stages and a mean minimum margin of 1.23 cm were required to achieve tumor clearance. Tumors on the head and neck required significantly more stages and a significantly wider margin. Tumor size was positively correlated with time to diagnosis, age, and number of MMS stages. CONCLUSION: Tumors located on the head and neck have greater subclinical extension. Tumor size was also a predictor of surgical difficulty, but time to diagnosis was not.

Effects of COVID-19 Lockdown on Tumour Burden of Melanoma and Cutaneous Squamous Cell Carcinoma.

The aim of this study was to compare tumour burden in patients who underwent surgery for melanoma and cutaneous squamous cell carcinoma during nationwide lockdown in Spain due to COVID-19 (for the period 14 March to 13 June 2020) and during the same dates in 2019 before the COVID-19 pandemic. In addition, associations between median tumour burden (Breslow thickness for melanoma and maximum clinical diameter for cutaneous squamous cell carcinoma) and demographic, clinical, and medical factors were analysed, building a multivariate linear regression model. During the 3 months of lockdown, there was a significant decrease in skin tumours operated on (41% decrease for melanoma (n = 352 vs n = 207) and 44% decrease for cutaneous squamous cell carcinoma (n = 770 vs n = 429)) compared with the previous year. The proportion of large skin tumours operated on increased. Fear of SARS-CoV-2 infection, with respect to family member/close contact, and detection of the lesion by the patient or doctor, were related to thicker melanomas; and fear of being diagnosed with cancer, and detection of the lesion by the patient or relatives, were related to larger size cutaneous squamous cell carcinoma. In conclusion, lockdown due to COVID-19 has resulted in a reduction in treatment of skin cancer.

Usefulness of ultrasound in dermatofibrosarcoma protuberans and correlation with histopathological findings: A series of 30 cases.

BACKGROUND: Small series of ultrasound findings in dermatofibrosarcoma protuberans (DFSP) have been published, but the usefulness of this technique as a preoperative planning tool for tumor resection has not been studied. MATERIALS AND METHODS: We retrospectively reviewed patients with DFSP at our hospital that underwent ultrasound examination. Depth of invasion was evaluated by ultrasound and histopathology. Accuracy of ultrasound for assessing depth of tumor invasion was estimated. RESULTS: Thirty histopathologically confirmed DFSPs were studied. Classic finger-like projections were observed in 73.3% of cases. A posterior hyperechoic area extending deep into the subcutaneous tissue correlated with the honeycomb DFSP pattern and was observed in 53.3% of patients. Concordance between ultrasound and histopathologic depth measurements was excellent. Lateral tumor extension and Doppler activity were not evaluated in our series. CONCLUSION: Ultrasound showed excellent prediction of depth of invasion. Further studies are required to define the usefulness of ultrasound for determining lateral tumor extension.

Pleomorphic dermal sarcoma: a retrospective study of 16 cases in a dermato-oncology centre and a review of the literature.

BACKGROUND: Relatively little is known about the true aggressive potential of pleomorphic dermal sarcoma (PDS) or optimal management strategies. OBJECTIVE: To describe the outcomes of 16 cases of PDS treated at our hospital (14 with modified Mohs micrographic surgery [M-MMS] and two with conventional surgery) and establish an adequate plan for management. MATERIALS & METHODS: We reviewed 16 PDS cases treated at our hospital between October 2007 and June 2019 and compared our results with the available evidence. RESULTS: In total, 69% of cases had recurred after initial conventional surgery, M-MMS led to local disease control in 83% of cases, and 19% of patients developed metastasis. Combining all published PDS cases with ours, we calculated an overall metastasis rate of 12%, and an overall recurrence rate of 35% after conventional surgery and 17% after M-MMS. CONCLUSION: PDS is more aggressive than previously estimated, with an overall metastatic rate of 12%. Despite high recurrence rates with previous conventional surgery (69%), M-MMS achieved a good rate of local disease control (83%). Given the potential aggressivity of PDS and the importance of clear surgical margins, M-MMS appears to be more adequate than conventional excision. Staging studies and close monitoring are warranted in PDS patients, for which we propose a management algorithm.

Intralesional Methotrexate for the Treatment of Advanced Keratinocytic Tumors: A Multi-Center Retrospective Study.

INTRODUCTION: Keratinocyte tumors (KT) are frequently observed. Surgery is the treatment gold standard. In some cases, a surgical approach might not be the best option. Radiotherapy (RT) and systemic treatments can frequently cause side effects or be contraindicated. Intralesional methotrexate (MTX) can be a conservative yet effective alternative. We decided to evaluate the effectiveness and safety of intralesional chemotherapy with MTX for the treatment of squamous cell carcinoma (SCC), keratoacanthoma (KA), and basal cell carcinoma (BCC). METHODS: All patients had a histologically confirmed diagnosis of BCC, SCC, or KA and no indication to surgery or RT. MTX was injected subcutaneously proceeding from the periphery of the lesion toward the center. Different protocols in terms of dose, frequency, and length of treatment were used to compare them. Treatment efficacy was evaluated in terms of tumor size reduction. Patients were divided into three groups: responders (improvement of more than 50%), partial responders (< 50%), and non-responders (no improvement or worsening). All data were analyzed using the chi-squared test (χ2). RESULTS: Thirty-five patients were included. Twenty-one patients suffered from SCC, 12 from KA, and 2 from BCC. KA showed a higher response rate than SCC and BCC. For AK, 92% of patients had a complete resolution; 8% were partial responders. For SCC, 47.6% of cases were responders and 14.3% partial responders, while 38% non-responders. All BCCs showed no improvement. A treatment protocol of weekly injections, performed for 4 to 6 weeks, was the most efficient. Doses of 25 mg/ml per session seemed to be most effective. About one third of our patients developed side effects with mild anemia being the most frequent. CONCLUSIONS: For selected cases, intralesional MTX can be a safe and effective option for the treatment of KT, especially in case of KA and, to a lesser extent, SCC.

Coding and noncoding somatic mutations in candidate genes in basal cell carcinoma.

Basal cell carcinoma (BCC) represents the most commonly diagnosed human cancer among persons of European ancestry with etiology mainly attributed to sun-exposure. In this study we investigated mutations in coding and flanking regions of PTCH1 and TP53 and noncoding alterations in the TERT and DPH3 promoters in 191 BCC tumors. In addition, we measured CpG methylation within the TERT hypermethylated oncological region (THOR) and transcription levels of the reverse transcriptase subunit. We observed mutations in PTCH1 in 58.6% and TP53 in 31.4% of the tumors. Noncoding mutations in TERT and DPH3 promoters were detected in 59.2% and 38.2% of the tumors, respectively. We observed a statistically significant co-occurrence of mutations at the four investigated loci. While PTCH1 mutations tended to associate with decreased patient age at diagnosis; TP53 mutations were associated with light skin color and increased number of nevi; TERT and DPH3 promoter with history of cutaneous neoplasms in BCC patients. Increased reverse transcriptase subunit expression was observed in tumors with TERT promoter mutations and not with THOR methylation. Our study signifies, in addition to the protein altering mutations in the PTCH1 and TP53 genes, the importance of noncoding mutations in BCC, particularly functional alterations in the TERT promoter.

Predictive Value of Sentinel Lymph Node Biopsy in Cutaneous Squamous Cell Carcinoma Based on the AJCC-8 and Brigham and Women's Hospital Staging Criteria.

BACKGROUND: Recommendations on when to perform sentinel lymph node (SLN) biopsy in cutaneous squamous cell carcinoma (cSCC) are lacking despite the tumor's clear predilection for lymphatic spread. OBJECTIVE: To analyze the frequency of SLN metastasis in published series of cSCC in the context of the eighth edition of the American joint Committee on Cancer (AJCC-8) and the Brigham and Women's Hospital (BWH) staging criteria. METHODS: Systematic review of studies of patients with cSCC who underwent SLN biopsy that described biopsy results. RESULTS: In total, 153 patients with 24 positive SLN biopsies (15.7%) were included. Based on the AJCC-8 criteria positivity rates in the T2 and T3 categories were 8.3% (1/12 patients) and 25% (8/32), respectively. Using the BWH system there were, 2/33 in category T2a (6.5%), and 5/17 in category T2b (29.8%). On applying the same criteria to tumors of the trunk and extremities the results were similar. CONCLUSION: It would seem reasonable to recommend SLN biopsy for patients with AJCC-8 Stage T3+ disease or BWH Stage T2b/T3 disease. Both the AJCC-8 and the BWH systems would appear to be useful for staging cSCC of the trunk and extremities.