Cutaneous mesenchymal tumours: an update

Hotspots and future trends of dermatofibrosarcoma protuberans

Objective

Dermatofibrosarcoma protuberans (DFSP) is a moderately malignant soft tissue sarcoma with localized infiltrative growth. The extensive surgical scope and high recurrence rate of DFSP brings dysfunctional, aesthetic, psychological and economic problems to patients. The aim of this study is to explore the global publication characteristics, research hotspots and future trends of DFSP over the past 32 years via an intuitive visualized way.

Methods

The Web of Science Core Collection (WoSCC) database was searched for papers related to DFSP published from 1990 to 2022. Then bibliometric analysis of these publications was performed, including collaborative networks, co-citation analysis of journals and references, and cluster analysis of keywords.

Results

A total of 1588 papers were retrieved between 1990-2022. The United States was the most prolific country, followed by China. The article Imatinib Mesylate in Advanced Dermatofibrosarcoma Protuberans: Pooled Analysis of Two Phase II Clinical Trials, received most citations. Research hotspots and future trends are mainly focused on disease diagnosis, COL1A1-PDGFB fusion gene, drug and surgical treatment, fibrosarcomatous transformation, and immunotherapy.

Conclusion

The research on DFSP faces several clinical challenges. This study provides novel insights into future research directions and scientific decisions for DFSP.

Mesenchymal Tumors of the Skin: A Review

Mesenchymal tumors of the skin are rare and clinically heterogeneous, and can represent diagnostic challenge for pathologists. Most of these lesions have overlapping clinical and histological features, thus the understanding of architectural patterns, cytoplasmic and stromal features can facilitate proper diagnosis. Anatomic site may be an important factor in the differential diagnosis, as are patient's age and sex. Ancillary tests are often required and can be useful to rule out other entities. Molecular diagnostics is playing an increasingly important role in the diagnosis of soft tissue neoplasms. Here, we review clinical, histological, and molecular features of some of the most common of these uncommon entities including benign and malignant lesions.

Increased Occurrence of Cutaneous Leiomyomas and Dermatofibromas in Patients with Uterine Leiomyomas without Fumarate Hydratase Gene Mutations

Leiomyomas are smooth muscle-derived benign neoplasms that can affect all organs, most frequently in the uterus. Fumarate hydratase gene (FH) mutation is characterised by an autosomal dominant disease with increased occurrence of renal tumours, but also by cutaneous (CLs) and uterine leiomyomas (ULs). So far, an increased occurrence of skin tumours in non-mutated patients with ULs has not been verified. To this aim, a case-group of women who were FH non-mutated patients surgically treated for ULs (n = 34) was compared with a control-group (n = 37) of consecutive age-matched healthy women. The occurrence of skin neoplasms, including CLs and dermatofibromas (DFs), was evaluated. Moreover, the microscopic features of FH non-mutated skin tumours were compared with those of an age-matched population group (n = 70) who presented, in their clinical history, only one type of skin tumour and no ULs. Immunohistochemical and in vitro studies analysed TGFβ and vitamin D receptor expression. FH non-mutated patients with ULs displayed a higher occurrence of CLs and DFs (p < 0.03 and p < 0.001), but not of other types of skin tumours. Immunohistochemistry revealed a lower vitamin D receptor (VDR) expression in CLs and DFs from the ULs group compared with those from the population group (p < 0.01), but a similar distribution of TGFβ-receptors and SMAD3. In vitro studies documented that TGFβ-1 treatment and vitamin D3 have opposite effects on α-SMA, TGFβR2 and VDR expression on dermal fibroblast and leiomyoma cell cultures. This unreported increased occurrence of CLs and DFs in FH non-mutated patients with symptomatic ULs with vitamin D deficiency suggests a potential pathogenetic role of vitamin D bioavailability also for CLs and DFs.

Challenging Patterns of Atypical Dermatofibromas and Promising Diagnostic Tools for Differential Diagnosis of Malignant Lesions

Dermatofibroma (DF) or fibrous histiocytoma is one of the most frequent benign cutaneous soft-tissue lesions, characterized by a post-inflammatory tissue reaction associated with fibrosis of the dermis. Clinically DFs have a polymorphous clinical aspect from the solitary, firm, single nodules to multiple papules with a relatively smooth surface. However, multiple atypical clinicopathological variants of DFs have been reported and, therefore, clinical recognition may become challenging, leading to a more burdensome identification and sometimes to misdiagnosis. Dermoscopy is considered an important tool in DFs diagnosis, as it improves diagnostic accuracy for clinically amelanotic nodules. Although typical dermoscopic patterns are most frequently seen in clinical practice, there have also been some atypical variants described, mimicking some underlying recurrent and sometimes harmful skin afflictions. Usually, no treatment is required, although an appropriate work-up may be necessary in specific cases, such as in the presence of atypical variants or a history of recent changes. This narrative review's aim is to summarize current evidence regarding clinical presentation, positive and differential diagnosis of atypical dermatofibromas and also to raise awareness about the importance of specific characteristics of atypical variants to better differentiate them from malignant conditions.

Transducing-Like Enhancer of Split 1: A Potential Immunohistochemical Marker for Glomus Tumor

Glomus tumors (GTs) are rare, perivascular soft tissue tumors. Although GTs are usually found in the subcutaneous tissue, they may be detected in extracutaneous sites and mucosal areas. Transducing-like enhancer of split 1 (TLE1) is a highly useful immunohistochemical marker, which basically helps in differential diagnosis of synovial sarcoma. Based on a coincidental detection of TLE1 in one GT case, we studied 26 additional GT cases to establish the importance and distribution of TLE1 in GTs. Of 24 subcutaneous GTs, 22 (91.6%) were positive for TLE1 antibody and the remaining 2 mucosal GTs were negative. Of the 22 positive cases, 10 showed strong nuclear positivity. There was no difference between the subtypes of the GTs. Although TLE1 expression is significantly correlated to SS18 (SYT) rearrangements in synovial sarcomas, the fluorescence in situ hybridization analyses of the GTs showed no evidence of translocation involving this locus. TLE1 is a potential immunohistochemical marker for GTs, but further studies are required to confirm this finding.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Dermatopathology 101. Part 2 - Skin tumors

The present CME article highlights fundamental aspects with respect to the histopathology of the most common skin tumors (epidermal, adnexal, melanocytic, and mesenchymal), their laboratory workup, as well as the importance of supplementary immunohistochemical and molecular studies. The information provided is meant to assist experienced clinicians in choosing the correct biopsy technique and in interpreting dermatopathology reports, and to provide dermatology residents with a better understanding of dermatopathology. Similar to inflammatory dermatoses, the diagnosis of skin tumors, too, requires the close cooperation between clinicians and dermatopathologists. The diagnostic quality and the resultant therapeutic approach can be significantly improved if this collaboration is based on the same dermatological understanding.

Whorling cellular perineurioma: A previously undescribed variant closely mimicking monophasic fibrous synovial sarcoma

The authors present a distinctive perineurioma (PN) variant which morphologically strongly resembles monophasic fibrous synovial sarcoma (MSS). The patients were 3 males and 1 female. The age ranged from 15 to 61years (mean: 44years). Locations included the sole, lower jaw, palm and foot. The tumor size ranged from 1.3cm to 2.5cm in the largest dimension (mean 1.8cm). Morphologically, all tumors had an identical, monotonous appearance. The perineurial cells were closely packed and created a confluent cellular whorls and/or sheets in a scarce stroma, with only focally discernible long, slender cytoplasmic processes typical for perineurial differentiation. The nuclei were rounded or slightly elongated to tapered, without nuclear atypia. Mitoses were rare to completely absent. Atypical mitoses, hemorrhage, necrosis or calcifications were not present. The proliferative index (Ki-67) was 1-3%. All analyzed tumors were positive for EMA, Claudin-1, GLUT-1 and negative with S100 protein, CD34, OSCAR, CK7 and TLE-1. Two cases were tested by fluorescence in situ hybridization and neither showed alterations of the SYT gene. One case studied by electron microscopy showed characteristic features of perineurial differentiation. Follow-up was available for two patients both of which showed no evidence of disease at 8years and 6months, respectively. Based on their bland morphology, perineurial features and presumably benign clinical outcome we propose the term "whorling cellular perineurioma" for these tumors, which may represent an extremely cellular variant of sclerosing PN. Awareness of this PN subtype and its distinction from MSS is of utmost clinical significance.

Intraocular inflammatory mass associated with lens-induced uveitis

Intraocular inflammatory tumefactions large enough to simulate neoplasms are uncommon. We report a patient with a large intraocular inflammatory mass composed of cells with features of histiocytes and myofibroblasts that was associated with lens-induced uveitis. The spindle cell mass appears to have arisen as an exaggerated response to exposed lens fibers. Although information from immunohistochemistry and cytogenetics has advanced the classification of inflammatory tumefactions, this case highlights the challenges in establishing the nature of these lesions.