Avelumab to treat Merkel cell carcinoma: real-life experience in a dedicated oncology center. / Avelumab en el tratamiento del carcinoma de células de Merkel: experiencia en vida real en un centro monográfico oncológico.

The arrival of immunotherapy has revolutioned the management of patients with metastatic Merkel cell carcinoma (MCC). We conducted an observational, retrospective study of 14 cases treated with avelumab. The response rate was 57%: complete response was reached in 29% of patients, and partial responses in 29%. The drug proved effective in 83% (5/6) of the patients with a single metastatic site. However, the disease progressed in 75% (3/4) of the patients with bone metastases. PD1-L expression, MCC polyomavirus (MCPyV) positivity, and an impaired neutrophil-to-lypmhocyte ratio (NLR) could not be associated with responses to the therapy. Avelumab is an effective and safe drug for the management of advanced MCC, and its effectiveness appears to be impacted by the number and location of metastases.

La presencia de infiltración linfovascular y de un alto número de mitosis se asocia a un mayor riesgo de recidiva en sarcoma pleomórfico dérmico / Lymphovascular Invasion and High Mitotic Count Are Associated With Increased Risk of Recurrence in Pleomorphic Dermal Sarcoma

Introducción y objetivo El fibroxantoma atípico (FXA) y el sarcoma pleomórfico dérmico (SPD) son neoplasias de origen mesenquimal poco frecuentes. Debido a la baja incidencia del SPD y a una nomenclatura históricamente confusa existe poca información acerca de la verdadera agresividad de este tumor. Realizamos el presente estudio con el objetivo de identificar qué características clínicas y/o histológicas del SPD son predictoras de riesgo de recidiva. Material y método Se diseñó un estudio bicéntrico observacional retrospectivo de 31 casos de SPD diagnosticados y tratados en el Hospital Clínico Universitario de Valencia y el Instituto Valenciano de Oncología, entre los años 2005 y 2020. Se realizó un análisis descriptivo de las características clínicas e histológicas, un análisis inferencial univariado y un análisis multivariado mediante la regresión de Cox. Resultados En el análisis univariado, la recidiva tumoral (p<0,001), la necrosis (p=0,020), la infiltración linfovascular (p=0,037), la infiltración perineural (p=0,041) y el número de mitosis (categorizado en categorizado en <18 y ≥18 por 10 campos de gran aumento) (p=0,093), se asociaron a una menor supervivencia libre de enfermedad. En el análisis multivariado, el número de mitosis (categorizado en <18 y ≥18) y la infiltración linfovascular (p<0,05) se asociaron a una menor supervivencia libre de enfermedad. Conclusión El SPD es un tumor agresivo, en el que la presencia de un alto recuento mitótico (≥18) y/o invasión linfovascular se asocian a un mayor riesgo de recidiva y a una peor supervivencia libre de enfermedad. La necrosis y la infiltración perineural, también son hallazgos que probablemente se asocien a una mayor agresividad tumoral (AU)

Background and objective Atypical fibroxanthoma and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors. Due to the low incidence of PDS and a historically confusing nomenclature, little is known about the true aggressiveness of this tumor. The aim of this study was to investigate clinical and histologic risk factors for recurrence in PDS. Material and methods Retrospective, observational, bicentric study of 31 PDSs diagnosed and treated at Hospital Clínico Universitario de Valencia and Instituto Valenciano de Oncología in Valencia, Spain, between 2005 and 2020. We described the clinical and histologic features of these tumors and performed univariate analysis and multivariate Cox regression analysis. Results In the univariate analysis, tumor recurrence (P<.001), necrosis (P=.020), lymphovascular invasion (P=.037), perineural invasion (P=.041), and mitotic count (<18 vs ≥18 mitoses per 10 high-power fields) (P=.093) were associated with worse disease-free survival. In the multivariate Cox regression analysis, mitotic count and lymphovascular invasion retained their significance as predictors of worse disease-free survival (P<.05). Conclusions PDS is an aggressive tumor in which a high mitotic count (≥18) and lymphovascular invasion are associated with a higher risk of recurrence and worse disease-free survival. Necrosis and perineural invasion are also probably linked to increased tumor aggressiveness (AU)

[Translated article] Lymphovascular Invasion and High Mitotic Count Are Associated With Increased Risk of Recurrence in Pleomorphic Dermal Sarcoma / La presencia de infiltración linfovascular y de un alto número de mitosis se asocia a un mayor riesgo de recidiva en el sarcoma pleomórfico dérmico

Background and objective Atypical fibroxanthoma and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors. Due to the low incidence of PDS and a historically confusing nomenclature, little is known about the true aggressiveness of this tumor. The aim of this study was to investigate clinical and histologic risk factors for recurrence in PDS. Material and methods Retrospective, observational, bicentric study of 31 PDSs diagnosed and treated at Hospital Clínico Universitario de Valencia and Instituto Valenciano de Oncología in Valencia, Spain, between 2005 and 2020. We described the clinical and histologic features of these tumors and performed univariate analysis and multivariate Cox regression analysis. Results In the univariate analysis, tumor recurrence (P<.001), necrosis (P=.020), lymphovascular invasion (P=.037), perineural invasion (P=.041), and mitotic count (<18 vs ≥18 mitoses per 10 high-power fields) (P=.093) were associated with worse disease-free survival. In the multivariate Cox regression analysis, mitotic count and lymphovascular invasion retained their significance as predictors of worse disease-free survival (P<.05). Conclusions PDS is an aggressive tumor in which a high mitotic count (≥18) and lymphovascular invasion are associated with a higher risk of recurrence and worse disease-free survival. Necrosis and perineural invasion are also probably linked to increased tumor aggressiveness (AU)

Introducción y objetivo El fibroxantoma atípico (FXA) y el sarcoma pleomórfico dérmico (SPD) son neoplasias de origen mesenquimal poco frecuentes. Debido a la baja incidencia del SPD y a una nomenclatura históricamente confusa existe poca información acerca de la verdadera agresividad de este tumor. Realizamos el presente estudio con el objetivo de identificar qué características clínicas y/o histológicas del SPD son predictoras de riesgo de recidiva. Material y método Se diseñó un estudio bicéntrico observacional retrospectivo de 31 casos de SPD diagnosticados y tratados en el Hospital Clínico Universitario de Valencia y el Instituto Valenciano de Oncología, entre los años 2005 y 2020. Se realizó un análisis descriptivo de las características clínicas e histológicas, un análisis inferencial univariado y un análisis multivariado mediante la regresión de Cox. Resultados En el análisis univariado, la recidiva tumoral (p<0,001), la necrosis (p=0,020), la infiltración linfovascular (p=0,037), la infiltración perineural (p=0,041) y el número de mitosis (categorizado en categorizado en <18 y ≥18 por 10 campos de gran aumento) (p=0,093), se asociaron a una menor supervivencia libre de enfermedad. En el análisis multivariado, el número de mitosis (categorizado en <18 y ≥18) y la infiltración linfovascular (p<0,05) se asociaron a una menor supervivencia libre de enfermedad. Conclusión El SPD es un tumor agresivo, en el que la presencia de un alto recuento mitótico (≥18) y/o invasión linfovascular se asocian a un mayor riesgo de recidiva y a una peor supervivencia libre de enfermedad. La necrosis y la infiltración perineural, también son hallazgos que probablemente se asocien a una mayor agresividad tumoral (AU)

Lymphovascular Invasion and High Mitotic Count Are Associated With Increased Risk of Recurrence in Pleomorphic Dermal Sarcoma. / La presencia de infiltración linfovascular y de un alto número de mitosis se asocia a un mayor riesgo de recidiva en sarcoma pleomórfico dérmico.

BACKGROUND AND OBJECTIVE: Atypical fibroxanthoma and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors. Due to the low incidence of PDS and a historically confusing nomenclature, little is known about the true aggressiveness of this tumor. The aim of this study was to investigate clinical and histologic risk factors for recurrence in PDS. MATERIAL AND METHODS: Retrospective, observational, bicentric study of 31 PDSs diagnosed and treated at Hospital Clínico Universitario de Valencia and Instituto Valenciano de Oncología in Valencia, Spain, between 2005 and 2020. We described the clinical and histologic features of these tumors and performed univariate analysis and multivariate Cox regression analysis. RESULTS: In the univariate analysis, tumor recurrence (P<.001), necrosis (P=.020), lymphovascular invasion (P=.037), perineural invasion (P=.041), and mitotic count (<18 vs ≥18 mitoses per 10 high-power fields) (P=.093) were associated with worse disease-free survival. In the multivariate Cox regression analysis, mitotic count and lymphovascular invasion retained their significance as predictors of worse disease-free survival (P<.05). CONCLUSIONS: PDS is an aggressive tumor in which a high mitotic count (≥18) and lymphovascular invasion are associated with a higher risk of recurrence and worse disease-free survival. Necrosis and perineural invasion are also probably linked to increased tumor aggressiveness.

Cemiplimab in Advanced Cutaneous Squamous Cell Carcinoma: Real-World Experience in a Monographic Oncology Center / Cemiplimab en el carcinoma de células escamosas cutáneo avanzado: experiencia del mundo real en un centro oncológico monográfico

Management of advanced cSCC is challenging, and many available systemic medications have modest efficacy. Cemiplimab has demonstrated efficacy in the treatment of advanced cSCC in clinical trials, but real-world data are still limited. With the objective of evaluating the efficacy of cemiplimab in a real-world clinical setting, we conducted a prospective observational study of 13 patients with advanced cSCC. Six patients (46%) had locally advanced disease, while 7 (54%) had metastatic disease. A total of 8 patients (62%) responded to cemiplimab. Five (38%) showed a partial response, while 3 (23%) showed a complete response. Four patients with an initial partial response presented subsequent disease progression during follow-up. Six patients (46%) developed AEs, most of which were mild (G1). PFS was 5.9 months, with a median follow-up was 9 months. In conclusion, cemiplimab demonstrated its utility in the treatment of advanced cSCC, with acceptable response rates, a remarkable number of complete responses, and a very good safety profile (AU)

El manejo del carcinoma de células escamosas cutáneo (cSCC) avanzado es complicado, siendo modesta la eficacia de muchos de los fármacos sistémicos disponibles. Cemiplimab ha demostrado su eficacia en el tratamiento del cSCC avanzado en ensayos clínicos, pero los datos del mundo real siguen siendo limitados. Con el objetivo de evaluar la eficacia de cemiplimab en un entorno clínico del mundo real, realizamos un estudio observacional prospectivo de 13 pacientes con cSCC avanzado. Seis pacientes (46%) tenían enfermedad localmente avanzada, mientras que 7 (54%) tenían enfermedad metastásica. Un total de 8 pacientes (62%) respondieron a cemiplimab, 5 (38%) mostraron una respuesta parcial y 3 (23%) mostraron una respuesta completa. Cuatro pacientes con respuesta parcial inicial presentaron una progresión de la enfermedad subsiguiente durante el seguimiento. Seis pacientes (46%) desarrollaron efectos secundarios, siendo leve la mayoría de los mismos (G1). La supervivencia libre de progresión fue de 5,9 meses, con un seguimiento medio de 9 meses. En conclusión, cemiplimab demostró su utilidad en el tratamiento del cSCC avanzado, con unas tasas de respuesta aceptables, un número destacable de respuestas completas y un perfil de seguridad muy bueno (AU)

[Artículo traducido] Cemiplimab en el carcinoma de células escamosas cutáneo avanzado: experiencia del mundo real en un centro oncológico monográfico / Cemiplimab in Advanced Cutaneous Squamous Cell Carcinoma: Real-World Experience in a Monographic Oncology Center

El manejo del carcinoma de células escamosas cutáneo (cSCC) avanzado es complicado, siendo modesta la eficacia de muchos de los fármacos sistémicos disponibles. Cemiplimab ha demostrado su eficacia en el tratamiento del cSCC avanzado en ensayos clínicos, pero los datos del mundo real siguen siendo limitados. Con el objetivo de evaluar la eficacia de cemiplimab en un entorno clínico del mundo real, realizamos un estudio observacional prospectivo de 13 pacientes con cSCC avanzado. Seis pacientes (46%) tenían enfermedad localmente avanzada, mientras que 7 (54%) tenían enfermedad metastásica. Un total de 8 pacientes (62%) respondieron a cemiplimab, 5 (38%) mostraron una respuesta parcial y 3 (23%) mostraron una respuesta completa. Cuatro pacientes con respuesta parcial inicial presentaron una progresión de la enfermedad subsiguiente durante el seguimiento. Seis pacientes (46%) desarrollaron efectos secundarios, siendo leve la mayoría de los mismos (G1). La supervivencia libre de progresión fue de 5,9 meses, con un seguimiento medio de 9 meses. En conclusión, cemiplimab demostró su utilidad en el tratamiento del cSCC avanzado, con unas tasas de respuesta aceptables, un número destacable de respuestas completas y un perfil de seguridad muy bueno (AU)

Management of advanced cSCC is challenging, and many available systemic medications have modest efficacy. Cemiplimab has demonstrated efficacy in the treatment of advanced cSCC in clinical trials, but real-world data are still limited. With the objective of evaluating the efficacy of cemiplimab in a real-world clinical setting, we conducted a prospective observational study of 13 patients with advanced cSCC. Six patients (46%) had locally advanced disease, while 7 (54%) had metastatic disease. A total of 8 patients (62%) responded to cemiplimab. Five (38%) showed a partial response, while 3 (23%) showed a complete response. Four patients with an initial partial response presented subsequent disease progression during follow-up. Six patients (46%) developed AEs, most of which were mild (G1). PFS was 5.9 months, with a median follow-up was 9 months. In conclusion, cemiplimab demonstrated its utility in the treatment of advanced cSCC, with acceptable response rates, a remarkable number of complete responses, and a very good safety profile (AU)

Cemiplimab in Advanced Cutaneous Squamous Cell Carcinoma: Real-World Experience in a Monographic Oncology Center. / [Artículo traducido] Cemiplimab en el carcinoma de células escamosas cutáneo avanzado: experiencia del mundo real en un centro oncológico monográfico.

Management of advanced cSCC is challenging, and many available systemic medications have modest efficacy. Cemiplimab has demonstrated efficacy in the treatment of advanced cSCC in clinical trials, but real-world data are still limited. With the objective of evaluating the efficacy of cemiplimab in a real-world clinical setting, we conducted a prospective observational study of 13 patients with advanced cSCC. Six patients (46%) had locally advanced disease, while 7 (54%) had metastatic disease. A total of 8 patients (62%) responded to cemiplimab. Five (38%) showed a partial response, while 3 (23%) showed a complete response. Four patients with an initial partial response presented subsequent disease progression during follow-up. Six patients (46%) developed AEs, most of which were mild (G1). PFS was 5.9 months, with a median follow-up was 9 months. In conclusion, cemiplimab demonstrated its utility in the treatment of advanced cSCC, with acceptable response rates, a remarkable number of complete responses, and a very good safety profile.

Clinicopathological features, MCPyV status and outcomes of Merkel cell carcinoma in solid-organ transplant recipients: a retrospective, multicentre cohort study.

BACKGROUND: The proportion of Merkel cell carcinomas (MCCs) in solid-organ transplant recipients (SOTR) harbouring Merkel cell polyomavirus (MCPyV) is unknown, as are factors affecting their outcomes. OBJECTIVE: To describe clinicopathological features of MCC in SOTR, investigate the tumoral MCPyV-status and identify factors associated with tumour outcomes. METHODS: Retrospective, international, cohort-study. MCPyV-status was investigated by immunohistochemistry and polymerase chain reaction. RESULTS: A total of 30 SOTR and 44 consecutive immunocompetent patients with MCC were enrolled. SOTR were younger at diagnosis (69 vs. 78 years, P < 0.001). Thirty-three percent of SOTR MCCs were MCPyV-positive vs. 91% of immunocompetent MCCs (P = 0.001). Solid-organ transplantation was associated with an increased cumulative incidence of progression (SHR: 3.35 [1.57-7.14], P = 0.002), MCC-specific mortality (SHR: 2.55 [1.07-6.06], P = 0.034) and overall mortality (HR: 3.26 [1.54-6.9], P = 0.002). MCPyV-positivity and switching to an mTOR inhibitor (mTORi) after MCC diagnosis were associated with an increased incidence of progression (SHR: 4.3 [1.5-13], P = 0.008 and SHR: 3.6 [1.1-12], P = 0.032 respectively) in SOTR. LIMITATIONS: Retrospective design and heterogeneity of SOTR cohort. CONCLUSIONS: MCPyV appears to play a less prominent role in the aetiopathogenesis of MCC in SOTR. SOTR have a worse prognosis than their immunocompetent counterparts and switching to an mTORi after the diagnosis of MCC does not improve progression.

Cemiplimab in Advanced Cutaneous Squamous Cell Carcinoma: Real-World Experience in a Monographic Oncology Center.

Management of advanced cSCC is challenging, and many available systemic medications have modest efficacy. Cemiplimab has demonstrated efficacy in the treatment of advanced cSCC in clinical trials, but real-world data are still limited. With the objective of evaluating the efficacy of cemiplimab in a real-world clinical setting, we conducted a prospective observational study of 13 patients with advanced cSCC. Six patients (46%) had locally advanced disease, while 7 (54%) had metastatic disease. A total of 8 patients (62%) responded to cemiplimab. Five (38%) showed a partial response, while 3 (23%) showed a complete response. Four patients with an initial partial response presented subsequent disease progression during follow-up. Six patients (46%) developed AEs, most of which were mild (G1). PFS was 5.9 months, with a median follow-up was 9 months. In conclusion, cemiplimab demonstrated its utility in the treatment of advanced cSCC, with acceptable response rates, a remarkable number of complete responses, and a very good safety profile.

Sonidegib in the Treatment of Locally Advanced Basal Cell Carcinoma. / Sonidegib en el tratamiento del carcinoma basocelular localmente avanzado.

Sonidegib is an antagonist of the transmembrane protein Smoothened in the Hedgehog signaling pathway. It is indicated for the treatment of locally advanced basal cell carcinoma (BCC) that is not amenable to curative surgery or radiotherapy. Sonidegib's efficacy and safety were demonstrated in the phase 2 BOLT trial, where 61% (95% CI, 48-72%) of patients with locally advanced BCC treated with sonidegib 200 mg achieved an objective response to treatment with a mean time to response of 4 months. The median duration of response was 26.1 months and the median progression-free survival was 22.1 months. The most common adverse events were muscle spasms (54.4%), hair loss (49.4%), and loss of taste (44.3%); most events were grade 1 or 2. In this review, we summarize the main findings on the efficacy, safety, and tolerability of sonidegib and discuss the management of locally advanced BCC with this drug.

Eritema papular semicircular recidivante: ¿nueva entidad o subtipo de eritema anular centrífugo? / Erythema Papulosa Semicircularis Recidivans: A New Entity or a Subtype of Erythema Annulare Centrifugum?

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Tratamiento de la necrobiosis lipoídica con terapia fotodinámica convencional: serie de 4 casos tratados con éxito / Conventional Photodynamic Therapy for Necrobiosis Lipoidica: Successful Treatment in a Series of 4 Cases

La necrobiosis lipoídica (NL) es una enfermedad granulomatosa crónica poco frecuente para la que existen multitud de tratamientos disponibles. No obstante, estos ofrecen habitualmente mínimos e inconsistentes resultados. En algunas publicaciones se describe el tratamiento con terapia fotodinámica (TFD) como tratamiento de segunda línea en casos refractarios, con resultados variables. Comunicamos 4 casos de NL tratados satisfactoriamente con TFD convencional con MAL y BF-200 ALA. Las 4 pacientes eran mujeres afectas de diabetes mellitus y todas habían recibido al menos 2 tratamientos previos con escaso resultado. Tras una media de 3,2 sesiones de TFD por lesión, las 4 pacientes presentaron una resolución completa de las lesiones, persistiendo únicamente atrofia residual

Necrobiosis lipoidica is a rare chronic granulomatous disease. Multiple treatment approaches are available, but results are generally minimal and inconsistent. Some publications report variable results with photodynamic therapy (PDT) as a second line of treatment for refractory cases. We report 4 cases of necrobiosis lipoidica treated satisfactorily with conventional PDT using methyl aminolevulinate or 5-aminolevulinic acid BF-200 as the photosensitizing agent. All 4 patients were women with diabetes mellitus who had undergone treatment at least twice in the past, with little improvement. The lesions resolved completely with PDT, leaving only residual atrophy after a mean of 3.2 sessions per lesión

Conventional Photodynamic Therapy for Necrobiosis Lipoidica: Successful Treatment in a Series of 4 Cases. / Tratamiento de la necrobiosis lipoídica con terapia fotodinámica convencional: serie de 4 casos tratados con éxito.

Necrobiosis lipoidica is a rare chronic granulomatous disease. Multiple treatment approaches are available, but results are generally minimal and inconsistent. Some publications report variable results with photodynamic therapy (PDT) as a second line of treatment for refractory cases. We report 4 cases of necrobiosis lipoidica treated satisfactorily with conventional PDT using methyl aminolevulinate or 5-aminolevulinic acid BF-200 as the photosensitizing agent. All 4 patients were women with diabetes mellitus who had undergone treatment at least twice in the past, with little improvement. The lesions resolved completely with PDT, leaving only residual atrophy after a mean of 3.2 sessions per lesion.

Funciones de los tutores de residentes de Dermatología / Functions of Dermatology Residents' Supervisors

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Anticonceptivos orales en dermatología / Oral Contraceptives in Dermatology

Los anticonceptivos orales son fármacos compuestos por un estrógeno y un progestágeno, habitualmente sintéticos, que inhiben la ovulación. En dermatología los anticonceptivos orales se emplean con 2 indicaciones principales: para evitar el embarazo cuando empleamos fármacos teratógenos y para tratar manifestaciones cutáneas de hiperandrogenismo. La mayoría de los anticonceptivos orales mejoran tanto el acné como el hirsutismo, sin embargo el empleo exclusivo de progestágenos como anticonceptivos, especialmente de primera o segunda generación puede agravar o desencadenar un acné, debido a su efecto androgénico. La trombosis es uno de los efectos secundarios más graves de los anticonceptivos orales y depende sobre todo de los estrógenos empleados y su dosis. Si atendemos solo al perfil trombótico, el anticonceptivo oral de elección debería ser el que combinara 30 o menos mig de etinilestradiol con el levonorgestrel. Por el contrario, si lo que queremos es tratar signos de androgenización, los anticonceptivos orales preferidos serán aquellos con progestágenos de efecto antiandrogénico

Oral contraceptives combine estrogen and progesterone to suppress ovulation. Synthetic forms are usually used. In dermatology, oral contraceptives are prescribed for 2 main reasons: to prevent pregnancy when teratogenic drugs must be taken and to treat skin manifestations of hyperandrogenism. Most oral contraceptives improve both acne and hirsutism, but the androgenic effect of progestogens - particularly if the contraceptive contains first- or second-generation progestogens- can trigger or exacerbate acne. One of the most serious side effects of oral contraceptives, thrombosis, is mainly caused by the estrogen component and its dose. If we mainly consider a contraceptive's thrombotic profile when prescribing, the choice would be to have 30 Mug or less of ethinyl estradiol combined with levonorgestrel. On the other hand, if our main objective is to treat signs of androgenization, we would prefer contraceptives containing progestogens with antiandrogenic effects

Oral Contraceptives in Dermatology. / Anticonceptivos orales en dermatología.

Oral contraceptives combine estrogen and progesterone to suppress ovulation. Synthetic forms are usually used. In dermatology, oral contraceptives are prescribed for 2 main reasons: to prevent pregnancy when teratogenic drugs must be taken and to treat skin manifestations of hyperandrogenism. Most oral contraceptives improve both acne and hirsutism, but the androgenic effect of progestogens - particularly if the contraceptive contains first- or second-generation progestogens- can trigger or exacerbate acne. One of the most serious side effects of oral contraceptives, thrombosis, is mainly caused by the estrogen component and its dose. If we mainly consider a contraceptive's thrombotic profile when prescribing, the choice would be to have 30µg or less of ethinyl estradiol combined with levonorgestrel. On the other hand, if our main objective is to treat signs of androgenization, we would prefer contraceptives containing progestogens with antiandrogenic effects.

Fístula parotídea tras biopsia cutánea: tratamiento con toxina botulínica / Parotid Fistula After Skin Biopsy: Treatment With Botulinum Toxin

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Histologic Changes During Treatment With Vismodegib in Locally Advanced Basal Cell Carcinoma: A Series of 19 Cases.

BACKGROUND: There are no large series describing cutaneous histologic changes during treatment with vismodegib in locally advanced basal cell carcinoma (BCC). OBJECTIVE: To analyze histologic changes in skin biopsy specimens from patients with locally advanced BCC treated with vismodegib. METHODS: A descriptive, retrospective study of patients with locally advanced BCC treated with vismodegib between June 2012 and December 2017 at the Instituto Valenciano de Oncología, Spain. Nineteen patients were biopsied before and during the treatment with vismodegib, and we compared histologic changes observed. RESULTS: Seven patients (37%) achieved complete response, which was characterized by replacement of tumor stroma with a hyaline scar, lymphocytic inflammatory infiltrate, keratin formation, and infundibular cysts. Twelve patients (63%) achieved partial response; 5 showed no phenotypic changes, whereas 7 showed histologic changes; 5 cases showed metatypical differentiation; and 2 cases presented squamous differentiation. We observed no cases of squamous cell carcinoma arising at vismodegib treatment sites and no association between initial histologic subtype and clinical response. LIMITATIONS: Many biopsy specimens were obtained by punch biopsy and may not be representative of the full tumors. We studied histologic changes only in complete and partial responses. CONCLUSION: Vismodegib can induce histologic changes toward metatypical or squamous differentiation of BCC in patients with partial response. Keratinizing phenomena were frequent, both in partial and complete response groups.