BackgroundUntil now, almost nothing is known about the tumorigenesis of atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS). Our hypothesis is that AFX is the non-infiltrating precursor lesion of PDS.Materials and MethodsWe performed the world-wide most comprehensive immunohistochemical and mutational analysis in well-defined AFX (n=5) and PDS (n=5).ResultsIn NGS-based mutation analyses of selected regions by a 17 hotspot gene panel of 102 amplicons we could detect TP53 mutations in all PDS as well as in the only analyzed AFX and PDS of the same patient. Besides, we detected mutations in the CDKN2A, HRAS, KNSTRN and PIK3CA genes.Performing immunohistochemistry for CTNNB1, KIT, CDK4, c-MYC, CTLA-4, CCND1, EGFR, EPCAM, ERBB2, IMP3, INI-1, MKI67, MDM2, MET, p40, TP53, PD-L1 and SOX2 overexpression of TP53, CCND1 and CDK4 was seen in AFX as well as in PDS. IMP3 was upregulated in 2 AFX (weak staining) and 4 PDS (strong staining).FISH analyses for the genes FGFR1, FGFR2 and FGFR3 revealed negative results in all tumors.ConclusionsUV-induced TP53 mutations as well as CCND1/CDK4 changes seem to play essential roles in tumorigenesis of PDS. Furthermore, we found some more interesting mutated genes in other oncogene pathways (activating mutations of HRAS and PIK3CA). All AFX and PDS investigated immunohistochemically presented with similar oncogene expression profiles (TP53, CCND1, CDK4 overexpression) and the single case with an AFX and PDS showed complete identical TP53 and PIK3CA mutation profiles in both tumors. This reinforces our hypothesis that AFX is the non-infiltrating precursor lesion of PDS.

Purpose: Pleomorphic dermal sarcoma (PDS) is a rare malignant cutaneous tumor with an unknown cell of origin. Locally defined tumors can be treated by curative excisions, whereas advanced stages of the disease are difficult to treat, using standard regimens.Experimental Design: We performed whole-exome sequencing on a cohort of 28 individuals and corresponding transcriptomic analysis on 21 patients, as well as quantitative IHC image analysis on 27 patients.Results: PDS exhibits a universally high mutational load (42.7 mutations/mega base) with an inflamed, immunogenic tumor microenvironment. Three cases of PDS showed response to immune checkpoint blockade. Local mutation rate variation together with mRNA expression data demonstrate that PDS form a distinct entity, with PDGFRB as a lineage marker. In addition, we found that PDS is of mesenchymal, fibroblastic differentiation.Conclusions: PDS is of fibroblastic differentiation and exhibits a strong susceptibility to immunotherapy, including a high mutational burden and an inflamed tumor microenvironment.

Background Pleomorphic dermal sarcomas (PDS) are frequent UV‐induced sarcomas of the skin of intermediate grade malignant potential. Despite the fact that PDS have a noteworthy potential to recur (up to 28%) as well as to metastasize (up to 20%), there are no specific clinical guidelines with respect to follow‐up these patients. Moreover, little is known about clinical, histological or molecular prognostic factors in PDS. Objective The aim of the present study was to identify risk factors to predict relapse in a large multicentre sample cohort of PDS which could aid to optimize personalized treatment recommendations regarding surgical safety margins and adjuvant radiotherapy. Methods Patients with a diagnosis of PDS were selected from nine European institutions based on the histopathologic criteria described by Fletcher. Clinicopathologic and follow‐up data were collected and statistically analysed calculating univariate hazard ratios with 95% confidence intervals by use of the Cox proportional‐hazards model and a significance level of P < 0.05. Patients with an incomplete excision of the tumour were excluded. Results Univariate Cox regression analysis of possible prognostic factors for progression‐free survival (PFS) performed in 92 patients revealed that an excision margin of <2 cm is significantly associated with relapse of PDS [hazard ratio 4.478 (95% CI 1.536–13.055), P = 0.006]. Ulceration of the tumour was associated with a significantly better prognosis [0.396 (0.174–0.904), P = 0.028] whereas adjuvant radiotherapy did not reach statistical significance to improve prognosis in patients with PDS [0.775 (0.231–2.593), P = 0.679]. Gender, age, immunosuppression, intratumoural necrosis, tumour location, vertical thickness or horizontal diameter did not significantly influence PFS in PDS. Conclusion We identified surgical safety margins of <2 cm and absence of ulceration as risk factors for relapse in patients with PDS. These findings may be implemented into both the primary treatment as well as the further monitoring of patients with PDS.

Despite growing clinical evidence of ablative fractional photothermolysis (AFP), little is known about the spatiotemporal molecular changes within the targeted compartments. Six subjects received three different single AFP treatments using a scanned 250 mum CO(2)-laser beam. Spatiotemporal changes of skin regeneration were estimated by immunohistochemical investigation (HSP70, HSP72, HSP47, TGFbeta, procollagen III, CD3, CD20, and CD68) in skin samples 1 h, 3 days, and 14 days postintervention. The remodeling was uniformly started by regrowth of the epidermal compartment followed by partial to complete replacement of the microscopic ablation zones (MAZ) by newly synthesized condensed procollagen III. From day 3 to 14, the number of macrophages as well as giant cells surrounding the MAZ increased. TGFbeta expression was highest 1 h to 3 days following AFP. HSP70 and HSP72 expressions were highest 3-14 days postintervention in the spinocellular layer leading to an upregulation of HSP47. AFP performed by a scanned CO(2)-laser results in an early epidermal remodeling, which is followed by a dermal remodeling leading to a replacement of the MAZ with newly synthesized (pro)-collagen. During this, an inflammatory infiltrate with CD3(+) and CD20(+) cells surrounds the MAZ. The count of macrophages and giant cells involved in the replacement of the necrotic zones seems to be crucial for wound healing.

Atypical fibroxanthomas (AFX) and pleomorphic dermal sarcomas (PDS) are frequent cutaneous sarcomas typically arising on sun-exposed skin in elderly patients. In contrast to AFX, which generally do not recur after complete excision, PDS locally recur in up to 50% and metastasize in up to 20%.We recently detected characteristic UV-induced TP53 mutations as potential driver mutation in almost all PDS investigated as well as activating PIK3CA and RAS gene mutations in around one third of our tumors representing targets for personalized treatments in patients with unresectable or metastasized PDS.In the present study, we identified amplifications and deletions in a small part of the PDS (6 of 27 cases) but not in AFX suggesting that copy number variations (CNV) might not be an initial event in tumor development but rather important during tumor progression. In addition to BRAF, KNSTRN, IDH1 and PDGFRA amplification, CNV analyses revealed deletions in the CDKN2A, KIT and PDGFRA genes. In cases where an appropriate FISH assay was established, the CNV results could be verified by FISH analysis.Amplification of BRAF, KIT or PDGFRA and/or losses of CDKN2A might represent bad prognostic markers, although larger studies are needed to clarify their association with prognosis or progression in PDS.