The rope sign, a typical and yet infrequent clue.

Cutaneous granulomatous reactions are diverse, both from the clinical and the pathological perspective. Most underlying pathophysiological aspects remain elusive. Interstitial granulomatous dermatitis and palisaded neutrophilic and granulomatous dermatitis have been claimed to be reactions to systemic disorders, such as infectious, inflammatory, or neoplastic conditions. Recently, the overarching term "reactive granulomatous dermatitis" has been coined to unify both entities. We herein report two cases of reactive granulomatous dermatitis presenting with the widely known, albeit infrequent "rope sign" and provide clinicopathological correlation. The two patients included a 53-year-old woman with enlarging erythematous plaques and underlying palpable cords on both sides of trunk near axillae (rope sign), and a 51-year-old woman with personal history of rheumatoid arthritis and a palpable cord on the left aspect of the trunk. Pathological findings were compatible with reactive granulomatous dermatitis in both cases. In conclusion, the rope sign represents a strikingly infrequent but decisive diagnostic clue of reactive granulomatous dermatitis.

Position paper on a simplified histopathological classification of basal cell carcinoma: results of the European Consensus Project.

BACKGROUND: Histopathological classification of basal cell carcinoma (BCC) has important prognostic and therapeutic implications, but reproducibility of BCC subtyping among dermatopathologists is poor. OBJECTIVES: To obtain a consensus paper on BCC classification and subtype definitions. METHODS: A panel of 12 recognized dermatopathologists (G12) from nine European countries used a modified Delphi method and evaluated 100 BCC cases uploaded to a website. The strategy involved five steps: (I) agreement on definitions for WHO 2018 BCC subtypes; (II) classification of 100 BCCs using the agreed definitions; (III) discussion on the weak points of the WHO classification and proposal of a new classification with clinical insights; (IV) re-evaluation of the 100 BCCs using the new classification; and (V) external independent evaluation by 10 experienced dermatopathologists (G10). RESULTS: A simplified classification unifying infiltrating, sclerosing, and micronodular BCCs into a single "infiltrative BCC" subtype improved reproducibility and was practical from a clinical standpoint. Fleiss' κ values increased for all subtypes, and the level of agreement improved from fair to moderate for the nodular and the unified infiltrative BCC groups, respectively. The agreement for basosquamous cell carcinoma remained fair, but κ values increased from 0.276 to 0.342. The results were similar for the G10 group. Delphi consensus was not achieved for the concept of trichoblastic carcinoma. In histopathological reports of BCC displaying multiple subtypes, only the most aggressive subtype should be mentioned, except superficial BCC involving margins. CONCLUSIONS: The three BCC subtypes with infiltrative growth pattern, characteristically associated with higher risk of deep involvement (infiltrating, sclerosing, and micronodular), should be unified in a single group. The concise and encompassing term "infiltrative BCCs" can be used for these tumors. A binary classification of BCC into low-risk and high-risk subtypes on histopathological grounds alone is questionable; correlation with clinical factors is necessary to determine BCC risk and therapeutic approach.

Tirbanibulin: review of its novel mechanism of action and how it fits into the treatment of actinic keratosis. / Tirbanibulina: revisión de su mecanismo de acción novedoso y de cómo encaja en el tratamiento de la queratosis actínica.

Actinic keratosis (AK) is a skin condition characterized by the proliferation of mutated keratinocytes that can develop into squamous cell carcinoma. Available therapies, although effective, are associated with a high frequency of severe local skin reactions. Tirbanibulin, one of the treatments for AK currently in development, is a new synthetic chemical entity with anti-proliferative and anti-tumor effects, both in vitro and in vivo, with proved efficacy in the treatment of AK, which has been recently demonstrated in two phase III clinical trials. In the present review, the tirbanibulin mechanism of action, based on the relevant literature and the results of several unpublished preclinical studies, is shown. In addition, the current scenario regarding the available treatments and how the novel tirbanibulin mechanism of action fits into the treatment of AK is raised.

Epithelial-to-mesenchymal transition contributes to invasion in squamous cell carcinomas originated from actinic keratosis through the differentiated pathway, whereas proliferation plays a more significant role in the classical pathway.

BACKGROUND: Every actinic keratosis (AK) starts with atypia at the basal layers of the epidermis (AK I). Progression into invasive squamous cell carcinoma (iSCC) may occur following two main pathways, classical and differentiated. In the former, iSCC only occurs after involvement of the upper epidermal layers by atypical cells (AK III), while in the latter iSCC develops directly from AK I. In the anogenital mucosa, these two pathways are associated with differential expression of p53 and p16. OBJECTIVE: To explore differences between both pathways in the pathogenesis of AK, focusing on Ki67, p53, p16 and molecules that reveal epithelial-mesenchymal transition (EMT). METHODS: Tissue microarrays representative of superficial and deep portions of 80 consecutive iSCCs (53 DP/27CP) were studied immunohistochemically using antibodies against Ki67, p53, p16, vimentin, E-cadherin, ß-catenin and D2-40. The evaluation was performed by three researchers and the results compared to consensus. RESULTS: Invasive squamous cell carcinomas originated through the differentiated pathway exhibited significantly lower proliferative activity (Ki67) (30% vs 46%, P = 0.003) and significantly lower expression of vimentin (P < 0.001), E-cadherin (P < 0.001) and membranous ß-catenin (P < 0.001) than iSCCs developed through the classical pathway. The expression of E-cadherin and membranous ß-catenin was significantly correlated (Pearson's r = 0.386, Spearman's Rho < 0.001). There were no significant differences regarding the expressions of p53, p16 and D2-40. CONCLUSION: Epithelial-mesenchymal transition participates in transformation from AK I into iSCC (differentiated pathway), whereas a higher proliferative capacity facilitates intraepidermal extension in the classical pathway. Podoplanin, which is also involved in tumour invasion, does not seem to play a differential role in either pathway. Finally, the absence of differences in p53 and p16 expressions is at variance with other epithelia where the classical pathway is associated with human papillomavirus infection and can be explained by the fact that both AK pathways share identical mechanisms of actinic oncogenesis.

The depth of follicular extension in actinic keratosis correlates with the depth of invasion in squamous cell carcinoma: implication for clinical treatment.

BACKGROUND: Actinic keratosis (AK) may show extension down follicles, not only in cases with full-thickness epidermal atypia ('bowenoid' AK), but also in cases with atypia limited to the epidermal basalis. Previous studies have demonstrated that, in bowenoid AK, follicular extension is usually superficial, being limited to the upper follicular segment. Little is known about the depth of follicular involvement in cases of invasive squamous cell carcinoma of the skin (iSCC) arising from AK and the role of the follicle in iSCC pathogenesis. OBJECTIVE: This study investigated the relationship between follicular extension of atypical keratinocytes in an AK and the development of iSCC from the follicular wall. The depth of follicular extension was correlated with the depth invasion of iSCC. Differences between the differentiated and classical pathways of iSCC were also examined. METHODS: We performed a retrospective histologic review of 193 biopsy specimens of iSCC with an associated AK. We assessed the presence and depth of follicular extension of atypical keratinocytes in the AK, using tumour (Breslow) thickness and the follicular unit level (infundibular, isthmic and subisthmic), as well as iSCC being present directly adjacent to the follicular basalis. RESULTS: Follicular extension was present in 25.9% of the cases (50 cases), usually extending into the lower follicular segment. The iSCC was present directly adjacent to the follicular basalis in 58% of the cases (29 cases), correlating highly with the depth of follicular extension (infundibular: 3/12; isthmic: 21/33; subisthmic 5/5). CONCLUSION: The depth of follicular extension of atypical keratinocytes in an AK correlates with the development of depth of invasion of an associated iSCC, irrespective of the pathway of origin. It is therefore important to note the presence and the depth of follicular extension when diagnosing an AK, as follicular extension likely accounts for a significant proportion of recurrent AK and the development of iSCC following superficial treatment modalities.

KIT mutations and CD117 overexpression are markers of better progression-free survival in vulvar melanomas.

BACKGROUND: Few studies have addressed prognostic markers and none has correlated molecular status and prognosis in vulvar melanomas. OBJECTIVES: To evaluate the clinicopathological features of 95 cases of vulvar melanoma. METHODS: p53, CD117, Ki-67, neurofibromin, brafv600e and nrasq61r immunostains, and molecular analyses by either targeted next-generation or direct sequencing, were performed on available archival materials. RESULTS: Molecular testing detected mutations in KIT (44%), BRAF (25%), NF1 (22%), TP53 (17%), NRAS (9%) and TERT promoter (9%). Co-mutation of KIT and NF1 and of KIT and NRAS were identified in two and one cases, respectively. KIT mutations were significantly associated with better progression-free survival in univariate analyses. In multivariate analyses CD117 expression was significantly associated with better progression-free survival. Tumour thickness was significantly associated with worse progression-free and overall survival, and perineural invasion significantly correlated with reduced melanoma-specific survival and reduced overall survival. Cases were from multiple centres and only a subset of samples was available for molecular testing. CONCLUSIONS: KIT mutations and CD117 overexpression are markers of better progression-free survival. In addition to its prognostic value, molecular testing may identify cases that might respond to targeted agents or immunotherapeutic approaches.

From actinic keratosis to squamous cell carcinoma: pathophysiology revisited.

The precursor of most cutaneous invasive squamous cell carcinomas (iSCCs) is intraepithelial UV-induced damage, known as field cancerization, which can eventually transform into actinic keratosis (AK). Although AK is the most common precursor of iSCC, many AKs will either persist in the same stage or regress, while only a few will progress into iSCC. Nevertheless, because the progression of individual AKs cannot be predicted, it has been proposed that all AKs, regardless of the grade, should be carefully monitored and appropriately treated in clinical practice. Modern imaging techniques such as dermatoscopy, reflectance confocal microscopy (RCM) and high-definition optical coherence tomography (HD-OCT) may have potential to monitor the evolution of actinic field damage. Dermatoscopy can be used to differentiate between AK, intraepidermal carcinoma (IEC) and SCC which may help clinicians to diagnose in situ or invasive lesions at an earlier stage. HD-OCT and RCM can be used to detect cellular and histological changes characteristic of subclinical lesions, allowing visualization of previously invisible lesions. As development of invasive AK directly from the cancer field cannot be ruled out, the ideal treatment should be able to eradicate AK lesions and reverse the underlying field cancerization.

Precancerous Skin Lesions. / Precáncer cutáneo.

Certain clinically and histologically recognizable skin lesions with a degree of risk of progression to squamous cell carcinoma have been traditionally grouped as precancerous skin conditions but now tend to be classified as in situ carcinomas. This consensus statement discusses various aspects of these lesions: their evaluation by means of clinical and histopathologic features, the initial evaluation of the patient, the identification of risk factors for progression, and the diagnostic and treatment strategies available today.

A cellular model reflecting the phenotypic heterogeneity of mutant HRAS driven squamous cell carcinoma.

Squamous cell carcinomas have a range of histopathological manifestations. The parameters that determine this clinically observed heterogeneity are not fully understood. Here, we report the generation of a cell culture model that reflects part of this heterogeneity. We have used the catalytic subunit of human telomerase hTERT and large T to immortalize primary UV-unexposed keratinocytes. Then, mutant HRAS G12V has been introduced to transform these immortal keratinocytes. When injected into immunosuppressed mice, transformed cells grew as xenografts with distinct histopathological characteristics. We observed three major tissue architectures: solid, sarcomatoid and cystic growth types, which were primarily composed of pleomorphic and basaloid cells but in some cases displayed focal apocrine differentiation. We demonstrate that the cells generated represent different stages of skin cancerogenesis and as such can be used to identify novel tumor-promoting alterations such as the overexpression of the PADI2 oncogene in solid-type SCC. Importantly, the cultured cells maintain the characteristics from the xenograft they were derived from while being amenable to manipulation and analysis. The availability of cell lines representing different clinical manifestations opens a new tool to study the stochastic and deterministic factors that cause case-to-case heterogeneity despite departing from the same set of oncogenes and the same genetic background.

Intravascular (blood vessel) histiocytosis with haemophagocytosis.

AIMS: Many types of intravascular lymphohistiocytic proliferation have been described recently; this was previously an unnoticed or misinterpreted phenomenon. Intralymphatic lymphohistiocytic aggregates are relatively common, and include benign, malignant and indeterminate conditions. In contrast, all non-endothelial proliferations in the lumina of blood vessels have been interpreted so far as malignant. Herein, we present three cases of histiocytic proliferations in the lumen of blood vessels associated with intracytoplasmic granulocyte debris (haemophagocytosis), a previously undescribed entity. METHODS AND RESULTS: We identified three patients from two institutions with similar cutaneous lesions, both clinically and microscopically. Information regarding clinical history, histological features and immunoprofiles were obtained. The three cases presented intravascular histiocytosis with haemophagocytosis involving blood vessels of the dermis, a process that may be representative of a new entity. The patients were two women and one man who presented a symmetrical reticulated erythema with a tendency to involve the skin of the breasts. The lesions were indolent, did not ulcerate and followed a benign course. CONCLUSION: This seemingly novel condition is characterized by the presence of histiocytic cells inside blood vessels, where they have not been described previously as an entity. The most reasonable explanation for this process is an origin from the non-classical subset of monocytes that 'patrol' the inner face of blood vessels acting as macrophages. The existence of this entity should be kept in mind to avoid overdiagnosis of malignancy.

Lupus erythematosus tumidus: a clinical and histological study of 25 cases.

BACKGROUND: Lupus erythematosus tumidus (LET) is a subtype of cutaneous lupus erythematosus (CLE) that has been well characterized in recent years. However, some controversy still remains concerning the histological features of epidermal involvement. OBJECTIVES: The objective of this report is to describe the clinical and microscopic features of LET in patients diagnosed at Hospital Universitari Germans Trias i Pujol, Spain. METHODS: We conducted a retrospective study of 25 patients with a diagnosis of LET. RESULTS: All patients presented with typical LET lesions (smooth, erythematous plaques without macroscopic epidermal changes, such as follicular plugs or scale, that resolved without residual scarring or hypopigmentation). None of the patients fulfilled the criteria for systemic lupus erythematosus during follow-up. Test results for antinuclear antibodies were positive in five patients (20%), with titres below one of 320 in all cases. Twenty-two patients (88%) required antimalarial therapy; response was good in 70% and moderate response in 30%. Minor epidermal alterations were observed in 52% of biopsy specimens, with focal basal vacuolization being the most frequent. CONCLUSIONS: LET is a variant of CLE that has distinctive clinical, histologic and prognostic features. Unlike the patients in the case series previously described in the literature, most of our patients required treatment with antimalarials. Histology revealed mild epidermal alterations in a significant percentage of patients. Thus, in our opinion, the absence of microscopic epidermal alterations is not constant in LET.