Pleomorphic Dermal Sarcoma: Adverse Histologic Features Predict Aggressive Behavior and Allow Distinction From Atypical Fibroxanthoma

Histopathologic Evaluation of Atypical Fibroxanthoma or Pleomorphic Dermal Sarcoma Debulk Specimen from Mohs Surgery: A Requirement for Their Proper Distinction

Pleomorphic dermal sarcomas can be clinically aggressive, with a higher tendency to cause local recurrence, metastasis, and death. Atypical fibroxanthoma and pleomorphic dermal sarcoma are histopathologically similar, and their distinction requires a systematic examination of the entire excised tumor. Since Mohs micrographic surgery is commonly utilized to treat atypical fibroxanthoma, a histopathologic evaluation of debulk specimens by permanent pathology is prudent to avoid underdiagnosing pleomorphic dermal sarcoma. This approach can improve risk assessment and treatment decisions, ultimately enhancing patient outcomes. Also, the proper distinction will facilitate the future development of accurate staging criteria and additional treatment modalities.

Proteomic analysis of pleomorphic dermal sarcoma reveals a fibroblastic cell of origin and distinct immune evasion mechanisms

Pleomorphic dermal sarcomas are infrequent neoplastic skin tumors, manifesting in regions of the skin exposed to ultraviolet radiation. Diagnosing the entity can be challenging and therapeutic options are limited. We analyzed 20 samples of normal healthy skin tissue (SNT), 27 malignant melanomas (MM), 20 cutaneous squamous cell carcinomas (cSCC), and 24 pleomorphic dermal sarcomas (PDS) using mass spectrometry. We explored a potential cell of origin in PDS and validated our findings using publicly available single-cell sequencing data. By correlating tumor purity (TP), inferred by both RNA- and DNA-sequencing, to protein abundance, we found that fibroblasts shared most of the proteins correlating to TP. This observation could also be made using publicly available SNT single cell sequencing data. Moreover, we studied relevant pathways of receptor/ligand (R/L) interactions. Analysis of R/L interactions revealed distinct pathways in cSCC, MM and PDS, with a prominent role of PDGFRB-PDGFD R/L interactions and upregulation of PI3K/AKT signaling pathway. By studying differentially expressed proteins between cSCC and PDS, markers such as MAP1B could differentiate between these two entities. To this end, we studied proteins associated with immunosuppression in PDS, uncovering that immunologically cold PDS cases shared a "negative regulation of interferon-gamma signaling" according to overrepresentation analysis.

UK guidelines for the management of soft tissue sarcomas

Soft tissue sarcomas (STS) are rare tumours arising in mesenchymal tissues and can occur almost anywhere in the body. Their rarity, and the heterogeneity of subtype and location, means that developing evidence-based guidelines is complicated by the limitations of the data available. This makes it more important that STS are managed by expert multidisciplinary teams, to ensure consistent and optimal treatment, recruitment to clinical trials, and the ongoing accumulation of further data and knowledge. The development of appropriate guidance, by an experienced panel referring to the evidence available, is therefore a useful foundation on which to build progress in the field. These guidelines are an update of the previous versions published in 2010 and 2016 [1, 2]. The original guidelines were drawn up by a panel of UK sarcoma specialists convened under the auspices of the British Sarcoma Group (BSG) and were intended to provide a framework for the multidisciplinary care of patients with soft tissue sarcomas. This iteration of the guidance, as well as updating the general multidisciplinary management of soft tissue sarcoma, includes specific sections relating to the management of sarcomas at defined anatomical sites: gynaecological sarcomas, retroperitoneal sarcomas, breast sarcomas, and skin sarcomas. These are generally managed collaboratively by site specific multidisciplinary teams linked to the regional sarcoma specialist team, as stipulated in the recently published sarcoma service specification [3]. In the UK, any patient with a suspected soft tissue sarcoma should be referred to a specialist regional soft tissues sarcoma service, to be managed by a specialist sarcoma multidisciplinary team. Once the diagnosis has been confirmed using appropriate imaging and a tissue biopsy, the main modality of management is usually surgical excision performed by a specialist surgeon, combined with pre- or post-operative radiotherapy for tumours at higher risk for local recurrence. Systemic anti-cancer therapy (SACT) may be utilised in cases where the histological subtype is considered more sensitive to systemic treatment. Regular follow-up is recommended to assess local control, development of metastatic disease, and any late effects of treatment.

A Retrospective Review and Comprehensive Tumour Profiling of Advanced Non-Melanomatous Cutaneous Spindle Cell Neoplasms Treated with Immune-Checkpoint Inhibitors

Non-melanomatous cutaneous spindle cell neoplasms are a rare group of malignancies that present a diagnostic challenge, and for which there is a lack of consensus on how to best manage patients with advanced disease and only limited reports of immune-checkpoint inhibitor (ICI) responses. In this study, we performed a single-center retrospective review of treatment outcomes for all advanced non-melanomatous cutaneous spindle cell neoplasms treated with ICIs. Blinded histopathology reviews occurred to confirm each diagnosis. Comprehensive tumour profiling included whole exome sequencing for tumour mutational burden (TMB) and ultraviolet(UV) signatures, and immunohistochemistry for immune-cell infiltration (CD4/CD3/CD8/CD103/CD20) and immune-checkpoint expression (PD-L1/LAG3/TIGIT). Seven patients were identified. The objective response rate was 86% (6/7) with five complete responses (CR). Responses were durable with two patients in CR > 30 months after ICI commencement. All patients had high TMB and UV signatures. One patient had PD-L1 100% (combined positive score) with abundant immune-cell infiltration and LAG3 expression. In advanced non-melanomatous cutaneous spindle cell neoplasms, excellent responses to ICIs with durable disease control were observed. ICIs are worthy of further exploration in these patients. UV signatures and high TMB could be used to help select patients for treatment.

Pleomorphic Dermal Sarcoma

Pleomorphic dermal sarcoma (PDS) is a rare cutaneous/subcutaneous neoplasm of purported mesenchymal differentiation that exists along a clinicopathologic spectrum with atypical fibroxanthoma (AFX). While PDS and AFX share histopathologic and immunohistochemical features, PDS exhibits deeper tissue invasion and has a higher rate of metastasis and local recurrence than AFX. Given its aggressive clinical course, early recognition and clinical management of PDS are essential for optimizing patient outcomes. This review aims to provide a brief overview of the clinicopathologic and molecular features, prognosis, and treatment of PDS.

Pleomorphic dermal sarcoma of the scalp - A single-centre experience

BACKGROUND

Pleomorphic dermal sarcoma (PDS) of the scalp is a rare tumour which is usually slow growing, but occasionally displays rapid growth and has a low rate of local recurrence. Surgical resection is the mainstay of treatment, with or without radiotherapy. The aim of this study is to describe the surgical approach and the additional benefit of radiotherapy to the treatment of these patients.

METHODS

Retrospective, single-centre analysis of patients with PDS of the scalp that underwent surgical resection between 2007 and 2021 (n = 24). Treatment variables including depth of resection (superficial or deep to the galea aponeurotica) and adjuvant radiotherapy were investigated.

RESULTS

Twenty-four patients were included in this study. Median age was 80 (range, 52-95), with a median ASA score of 3 (2-3). Sixteen (66.6 %) patients underwent surgical resection including the galea, while the rest (n = 8) did not or was not known. Radiotherapy was given in 7 (29 %) patients in which only 3 (12.5 %) were in the galeal resection group. Reasons for radiotherapy administration were concomitant SCC found at the same area of resection and close margins. In a median follow-up of was 26.2 months (range, 13.6-102.5) there was only one recurrence event.

CONCLUSIONS

PDS of the scalp can be safely managed with a surgical resection if clear surgical margins are achieved without radiotherapy with good oncological outcomes.

A Case of Pleomorphic Dermal Sarcoma: Giant Exophytic Tumor of the Medial Canthus

We present the case of a 99-year-old Caucasian female who was referred for treatment of a painless, 8.0 cm × 7.8 cm exophytic, pedunculated, ulcerated tumor of the left medial canthus. Pathology showed spindled, oval, and polygonal cells with pleomorphic nuclei. Many multinuclear giant cells and mitotic figures were also noted. The tumor was highlighted with CD10, showed focal positivity with actin, desmin, and CD68, and had increased Ki67 immunohistochemical staining. The tumor was negative for pancytokeratin, CK5/6, p63, MART-1/MelanA, S100, Sox10, p40, CD34, and CD23. Based on clinicopathologic correlation, the diagnosis of pleomorphic dermal sarcoma (PDS) was made. Pleomorphic dermal sarcoma (PDS) refers to a deep, histologically high-grade tumor that often resembles other tumors clinically and histologically. As PDS is frequently aggressive and related to adverse outcomes, it is important to recognize its distinguishing features in comparison to other similar entities, including atypical fibroxanthoma (AFX) and pleomorphic leiomyosarcoma (PLMS). To our knowledge, there is only one other reported case in the literature of PDS occurring on the eye. By reviewing and understanding characteristic etiologies, locations of presentation, histopathological features, and management techniques, pathologists can make a more accurate diagnosis and dermatologists can provide more effective patient care in a timely manner.

PRAME Expression Is a Useful Tool in the Diagnosis of Primary and Metastatic Dedifferentiated and Undifferentiated Melanoma

Although mostly recognized in the metastatic setting dedifferentiated and undifferentiated melanomas are increasingly recognized as cutaneous and, less commonly, mucosal primary tumors. Their diagnosis is challenging and dependent on sampling and recognition of a conventional melanoma precursor and/or detection of a mutation in a conventional melanoma driver gene. PRAME immunohistochemistry has recently become an important ancillary tool in the separation of melanoma from benign nevi, but no comprehensive studies exist regarding its value in the detection of dedifferentiated and undifferentiated melanomas and their separation from atypical fibroxanthoma and pleomorphic dermal sarcoma, the main differential diagnoses on sun-damaged skin. After retrieval from archival files, we performed PRAME immunohistochemistry on 11 primary and 10 metastatic dedifferentiated and undifferentiated melanomas, 11 atypical fibroxanthomas, and 10 pleomorphic dermal sarcomas. Nuclear staining was assigned extent (ranging from 0 to 4 and reflecting the percentage of PRAME-positive tumor nuclei) and intensity scores (graded as absent, weak, moderate, and strong, with assigned scores ranging from 0 to 3) with combined scores ranging from 0 to 7. Both primary and metastatic dedifferentiated and undifferentiated melanomas showed strong and diffuse nuclear PRAME staining with median combined scores of 7. Strong and diffuse staining was also seen in all conventional melanoma precursors except for desmoplastic melanoma. In contrast, PRAME staining in atypical fibroxanthoma and pleomorphic dermal sarcoma was patchy and weak with median combined scores of 2. Our data emphasize the diagnostic utility of PRAME staining as a first screening tool in the detection and workup of dedifferentiated and undifferentiated melanomas, both in the primary and metastatic settings. PRAME immunohistochemistry is particularly helpful as it is also positive in tumors without a recognizable conventional melanoma precursor and in those associated with desmoplastic melanomas, where PRAME is typically found to be negative.

Atypical fibroxanthoma and pleomorphic dermal sarcoma: Local recurrence and metastasis in a nationwide population-based cohort of 1118 patients

BACKGROUND

The prognosis of patients with atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) remains uncertain and no standardized follow-up programs have been established.

OBJECTIVE

To recommend a standardized follow-up program of patients with AFX and PDS based on nationwide long-term estimates of local recurrence and metastasis.

METHODS

All patients with AFX and PDS in Denmark between 2002 and 2022 were included. Danish National Registries were used to estimate the risks of local recurrence and metastasis for AFX and PDS.

RESULTS

The 5-year risk of local recurrence was 10% for AFX and 17% for PDS. The 5-year risk of metastasis was 0.8% for AFX and 16% for PDS. PDS metastasized within 3 years in >90% of the patients with the lungs as the primary metastasis site (50%). Invasion beyond the subcutis, perineural/intravascular infiltration, and increasing age significantly increased the risk of PDS relapse.

LIMITATIONS

Risk of misclassification and lack of detailed surgical information.

CONCLUSION

The follow-up of patients with AFX can be limited to clinical visits for 4 years. Patients with PDS should be followed with clinical visits and PET/CT twice a year for the first 3 years and once a year for a minimum of 1 year.

Dedifferentiated and undifferentiated melanomas: a practical approach to a challenging diagnosis

Dedifferentiation, defined as the loss of cellular features of terminal differentiation resulting in a more primitive, unspecialized phenotype, is a rare phenomenon in melanoma and more commonly observed in the metastatic setting than in primary melanomas. The diagnosis of dedifferentiated melanoma poses a significant challenge, and the tumors need to be carefully sampled and worked up to identify any residual morphologic, immunohistochemical, or molecular evidence of their melanocytic lineage. This article reviews our current knowledge of the clinical, histopathological, immunohistochemical, and molecular features of these rare tumors and provides a practical diagnostic approach and discussion of the relevant differential diagnoses and associated diagnostic pitfalls.

Pleomorphic Dermal Sarcoma With Metastasis to the Lung: A Case Report

ABSTRACT

Atypical fibroxanthoma and pleomorphic dermal sarcoma (PDS) are dermal malignant mesenchymal tumors that lie at the ends of the same disease spectrum. Clinically indistinguishable from atypical fibroxanthoma, PDS has a more aggressive course with significantly higher rate of local recurrence and metastases. Histological findings that favor a PDS include subcutaneous invasion, tumor necrosis, lymphovascular invasion, and/or perineural infiltration. Herein, we report a case of PDS with metastasis to the lung. Our report highlights the risk of local recurrence and metastatic spread in this cutaneous tumor and the importance of distinguishing this entity from its less aggressive counterpart.

Fine needle aspiration cytopathology of pleomorphic dermal sarcoma

INTRODUCTION

Pleomorphic dermal sarcoma (PDS) is an uncommon cutaneous mesenchymal neoplasm. It is cytomorphologically identical to atypical fibroxanthoma (AFX), but differs due to its invasion beyond the dermis. We undertook an examination of our experience with fine needle aspiration (FNA) biopsy cytology of PDS.

MATERIALS AND METHODS

Our cytopathology files were searched for examples of PDS with concomitant histopathological verification. FNA biopsy smears and cell collection were performed using standard techniques.

RESULTS

Seven cases of PDS were retrieved from four different patients (M:F, 1:1; age range: 63-88 years; mean age = 78 years). All patients (57%) presented with a primary tumour with one having an FNA biopsy of two local recurrences and a single distant metastasis. Five aspirates were from the extremities and two from the head/neck. Tumours ranged from 1.0 to 3.5 cm (mean, 2.2 cm). Specific cytological diagnoses were pleomorphic spindle/epithelioid sarcoma (3 cases), PDS (2), AFX (1), and atypical myofibroblastic lesion, query nodular fasciitis (1). Immunohistochemical (IHC) staining from FNA-generated cell blocks in two cases showed non-specific staining with vimentin in both cases; positive CD10, CD68, and INI-1 staining in one case; and smooth muscle actin expression in the other. Multiple negative stains were performed in both of these cases to exclude malignant melanoma, carcinoma, and specific forms of sarcoma. Cytopathology consisted of a mixture of spindle, epithelioid, and bizarre pleomorphic cells.

CONCLUSION

Coupled with ancillary IHC stains, FNA biopsy can help recognise PDS as a sarcomatous cutaneous neoplasm, but is unable to distinguish PDS from AFX.

Pleomorphic dermal sarcoma: it might be rare but it exists

Pleomorphic dermal sarcoma (PDS) is a rare mesenchymal tissue tumor. Its differential diagnosis from similar tumors, such as low differentiated squamous cell carcinoma, fibrosarcoma, desmoplastic melanoma, atypical fibroxanthoma (AFX), may be difficult, as they have similar clinical and histological presentation. We present a case of an 83-year-old man exhibiting an exophytic scalp lesion. Excision of the lesion was performed, ensuring clear surgical margins and pathologic examination revealed an invasive pleomorphic dermal sarcoma. This case highlights a rare case of a large pleomorphic dermal sarcoma, and it discusses the histological, molecular features, its differential diagnosis and management of PDS.

Cutaneous sarcoma: a review and practical approach to management

Sarcomas arising in the skin are rare but potentially fatal. These tumours originate from mesenchymal cells and can be divided between those that arise in soft tissue and those arising from bone. General guidelines exist for the management of soft-tissue sarcomas; however, there are no specific guidelines for cutaneous sarcomas. Current literature was reviewed for management of seven cutaneous sarcomas including atypical fibroxanthoma, pleomorphic dermal sarcoma, dermal and subcutaneous leiomyosarcoma, dermatofibroma sarcoma protuberans, Kaposi sarcoma, cutaneous angiosarcoma and malignant peripheral nerve sheath tumour. All suspected sarcomas should be discussed in a sarcoma multidisciplinary team meeting. This article is not a clinical guideline but should serve as a practical summary of how these tumours present, how they are recognized histologically, and how best to manage and follow-up patients. The aim is to support clinicians and facilitate the best and most evidence-based standard of care available.

Expression of SATB2 in primary cutaneous sarcomatoid neoplasms: a potential diagnostic pitfall

SATB2 can be used as an immunohistochemical marker for osteoblastic differentiation. The differential diagnosis of a cutaneous sarcomatoid neoplasm sometimes includes osteosarcoma when the tumour concomitantly involves the skin, soft tissue, and bone, or when there is a past medical history of osteosarcoma. As the utility of SATB2 immunohistochemistry in these scenarios was unclear, we aimed to determine the frequency and the pattern of SATB2 expression in a variety of cutaneous sarcomatoid neoplasms. SATB2 expression by immunohistochemistry was evaluated by intensity (0-3) and extent (0-100%) of staining to generate an h-score for each case. Expression levels were classified into high-positive (h-score ≥100), low-positive (20-99), and negative (<20) groups. Positive SATB2 expression was observed in 18/23 (78%) atypical fibroxanthomas (AFX), 10/19 (53%) pleomorphic dermal sarcomas, 9/20 (45%) cutaneous sarcomatoid squamous cell carcinomas, 14/39 (36%) sarcomatoid melanomas, 2/13 (15%) poorly differentiated cutaneous angiosarcomas, 10/17 (59%) high-grade cutaneous leiomyosarcomas, and 7/8 (88%) osteosarcoma controls. With the exception of AFX, all cutaneous neoplasms showed significantly lower average h-scores than osteosarcoma. AFX gave the highest average h-score (71) and percentage of high-positive cases (48%) among all examined cutaneous neoplasms. Only two (1.5%) of all cutaneous cases showed strong intensity of staining. Common SATB2 expression in various cutaneous sarcomatoid neoplasms poses a potential diagnostic pitfall when the differential diagnosis includes osteosarcoma. Requirement of strong staining and a high-positive h-score improves the specificity of SATB2 in differentiating these tumours from osteosarcoma.

Atypical Fibroxanthoma: Outcomes from a Large Single Institution Series

BACKGROUND

Atypical fibroxanthomas (AFX) are rare malignant cutaneous neoplasms. Unfortunately, limited clinicopathologic and outcomes data on this cancer exists.

OBJECTIVE

We report the clinical, pathologic, and treatment characteristics, as well as oncologic outcomes in this single-institution retrospective analysis.

METHODS

This retrospective cohort study compiled clinical, pathologic, treatment, and outcome data for all patients with AFX on definitive excision diagnosed, evaluated, and treated primarily by surgical resection at a single institution between 2000-2020. Descriptive statistics evaluated clinical and pathologic characteristics. Kaplan-Meier method and Cox proportional-hazards models were used to evaluate overall survival and recurrence-free survival.

RESULTS

78 patients with AFX were identified. The majority were elderly, immunocompetent, Caucasian men. 85% of tumors were located on the head and neck. 63% of patients were correctly diagnosed only after complete resection of the index lesion. The median surgical margin was 1.0 cm. Overall, only 1.3% (1/78) of patients developed a local recurrence (RFS). No patients died of disease.

CONCLUSION

This study suggests that resection margins of 1 cm achieve excellent local control with close to 99% RFS and 100% disease-specific survival.

Increase of atypical fibroxanthoma and pleomorphic dermal sarcoma: a retrospective analysis of four German skin cancer centers

BACKGROUND AND OBJECTIVES

In recent years, considerable insight has been gained into the pathogenesis, diagnosis and treatment of cutaneous sarcomas, including atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS). Both entities have shown increasing incidence rates in the last decade. This study was initiated to evaluate how these new insights impact the number of diagnoses of AFX/PDS compared to other cutaneous sarcoma entities.

PATIENTS AND METHODS

In a retrospective study of four German skin cancer centers, all histopathological reports of cutaneous sarcomas (AFX, PDS, dermatofibrosarcoma protuberans, cutaneous leiomyosarcoma, angiosarcoma, and Kaposi sarcoma) confirmed by board-certified dermatopathologists were analyzed during a time-period of seven years (2013-2019). Additionally, utilization of immunohistochemical markers (including pan-cytokeratin, S100, desmin, CD34, CD10, procollagen-1, CD99, CD14, and CD68) as an adjunct to diagnose AFX/PDS was recorded.

RESULTS

Overall, 255 cutaneous sarcomas were included in the present study. The diagnosis of a cutaneous sarcoma has consequently risen from 2013 to 2019 (from 16 to 52 annual cases). The results of AFX/PDS revealed 4.6 times more diagnoses in 2019 than in 2013. Atypical fibroxanthoma represented the most common subtype, displaying 49.3 % of all diagnosed cutaneous sarcomas. Additionally, the increase of AFX/PDS was linked to the use of immunohistochemistry, with specific immunohistochemical markers used in 57.1 % of cases in 2013 compared to 100 % in 2019.

CONCLUSIONS

This retrospective study of four German skin cancer centers demonstrates a substantial rise of AFX/PDS, possibly due to recently established diagnostic and terminology standards. This rise is probably linked to increased utilization of specific immunohistochemical markers. Atypical fibroxanthoma/PDS may be more common than previously thought and seems to represent the most frequent cutaneous sarcoma subtype.

Zunahme des atypischen Fibroxanthoms und pleomorphen dermalen Sarkoms: eine retrospektive Analyse vier deutscher Hauttumorzentren

HINTERGRUND UND ZIELE

In den letzten Jahren konnten umfassende Erkenntnisse über die Pathogenese, Diagnostik und Behandlung von kutanen Sarkomen, insbesondere des atypischen Fibroxanthoms (AFX) und pleomorphen dermalen Sarkoms (PDS) gesammelt werden. Beide Entitäten zeigten innerhalb der letzten Dekade steigende Inzidenzraten. Die vorliegende Studie diente der Untersuchung, welchen Einfluss die neuen Erkenntnisse auf die Fallzahlen von AFX/PDS im Vergleich zu anderen Sarkom-Entitäten haben.

PATIENTEN UND METHODIK

Diese retrospektive Studie wurde an vier deutschen Hauttumorzentren durchgeführt und alle von zertifizierten Dermatopathologen bestätigten histopathologischen Befunde von kutanen Sarkomen (AFX, PDS, Dermatofibrosarcoma protuberans, kutanes Leiomyosarkom, Angiosarkom und Kaposi-Sarkom) in einem Zeitraum von sieben Jahren (2013-2019) evaluiert. Zusätzlich wurde der Einsatz von immunhistochemischen Markern als diagnostische Hilfe (Panzytokeratin, S100, Desmin, CD34, CD10, Prokollagen-1, CD99, CD14 und CD68) erfasst.

ERGEBNISSE

Insgesamt konnten 255 kutane Sarkome in die vorliegende Studie eingeschlossen werden. Die Zahl der kutanen Sarkome nahm kontinuierlich von 2013 bis 2019 zu (von 16 auf 52 Fälle im Jahr). Die Diagnose eines AFX/PDS konnte in 2019 4,6-mal häufiger als in 2013 gestellt werden. Das AFX stellte mit 49,3 % aller kutanen Sarkome den häufigsten Sarkom-Subtypen dar. Zusätzlich war der Anstieg von AFX/PDS mit dem Einsatz von Immunhistochemie assoziiert. Der Einsatz von spezifischen Immunhistochemischen Markern stieg von 57,1 % im Jahr 2013 auf 100 % in 2019.

SCHLUSSFOLGERUNGEN

Diese retrospektive Studie von vier deutschen Hauttumorzentren demonstriert eine substanzielle Zunahme von AFX/PDS, wahrscheinlich infolge kürzlich etablierter beziehungsweise verbesserter diagnostischer und terminologischer Standards. Dieser Anstieg ist vermutlich mit dem vermehrten Einsatz von bestimmten immunhistochemischen Markern assoziiert. AFX/PDS treten wahrscheinlich häufiger auf als bisher vermutet und repräsentieren möglicherweise den häufigsten kutanen Sarkom-Subtyp.

Immune checkpoint inhibitors for unresectable or metastatic pleomorphic dermal sarcomas

Pleomorphic dermal sarcomas (PDS) are rare neoplasms of the skin that occur in UV-exposed sites in the elderly, but represent the most common cutaneous sarcomas. Although the majority of PDS can be surgically removed, local recurrences occur in up to 28%, usually occurring within the first two years after primary excision. Metastases are diagnosed in up to 20% of cases, mainly observed in the skin, lymph nodes and lungs, preferentially affecting patients with underlying hemato-oncologic diseases. Similar to other UV-induced tumors, PDS are inflammatory and immunogenic tumors (with a high number of CD4+/CD8+ tumor-infiltrating lymphocytes (TILs) and checkpoint molecule expression such as PD-L1, LAG-3, TIGIT) with a very high mutational burden. The most common genetic alterations include UV-induced TP53 loss of function mutations, followed by alterations in the CDKN2A/B gene. Rarely, targetable genetic alterations can be detected. Compelling experimental data and clinical reports about PD-1/PD-L1-blocking antibodies in patients with PDS suggest its use as first line treatment in unresectable or metastatic tumor stages. However, individual ("off-line") patient management should be discussed in an interdisciplinary tumor board based on molecular genetic testing, mutational burden, PD-L1 expression, and evidence of tumor-infiltrating lymphocytes in addition to comorbities of the individual patient.

Prognostic factors for pleomorphic dermal sarcoma: analysis of 1911 cases from the SEER database

Prognostic factors for pleomorphic dermal sarcoma, a rare undifferentiated neoplasm of the skin, are poorly defined, and typical staging systems do not appear to be appropriate for these neoplasms. We; therefore, sought to identify prognostic factors for disease-specific survival and predictors of metastasis.

Pleomorphic dermal sarcomas were identified in the Surveillance, Epidemiology and End Results database (N=1911). Multiple imputation was used to overcome inherent limitations in this dataset to assess prognostic factors using multivariable Cox proportional hazard stratified by (neo)adjuvant radiotherapy and logistic regression for presentation with metastasis.

Age, tumour size and metastasis were independent prognostic factors for cutaneous sarcoma-specific survival. Only tumour size was associated with increased odds of presentation with metastasis, with tumours >4 cm at highest risk. Metastasis is the most important factor in determining outcomes, with age and size as lesser factors. Only tumour size is predictive of metastasis, with larger tumours at highest risk.

Skin Photodamage Lesions in a Bilateral Feline Auricular Primary Fibrosarcoma

As with human species, recent studies also suggest a photoinduced etiopathology for non-epithelial cutaneous tumors in feline species. We report a recent case of a ten-year-old male cat with a white-hair coat and mesenchymal neoplasms of both auricles. Cytology, complete blood count (CBC), serum biochemistry and imaging examinations were performed. After surgery, the samples underwent routinary histopathology and were additionally stained with orcein. A routine analysis yielded values within a normal range and the imaging examination showed no abnormalities, suggesting that the bilateral presentation of neoplasms was primary rather than metastatic. The cytology was inconclusive, but, through histopathology, two well-differentiated fibrosarcomas were diagnosed and histopathological changes related to chronic UV exposure (such as epidermal hyperplasia, stratification disorders, keratinocyte dysplasia and an accumulation of elastotic material) were documented in the skin adjacent to the lesions. An orcein stain succeeded in highlighting elastosis. The elastic fibers lost their regular structure and orientation and appeared to be fragmented, wavy to branched and knotted. A morphometric analysis showed that the amount of elastotic material in the dermis close to the tumors was more than double compared with the more distant areas. Elastosis is considered to be a hallmark of photodamage; thus, an involvement of UV rays in the carcinogenic process of the tumors may be suspected.

Clear cell variant of atypical fibroxanthoma and pleomorphic dermal sarcoma: molecular characterization and review of the literature

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are unusual cutaneous tumors that typically arise in sun-damaged skin of elderly individuals. Several histopathologic variants have been described, but the clear cell variant is particularly rare with only 18 cases of AFX and 1 case of PDS reported. Here, we present two cases of clear cell AFX and PDS highlighting key histopathologic findings and molecular alterations assessed by next generation sequencing (NGS).

Oncological Safety and Recurrence in the Surgical Treatment of Atypical Fibroxanthoma and Pleomorphic Dermal Sarcoma of the Scalp

Simple Summary

Atypical fibroxanthoma and pleomorphic dermal sarcoma represent two tumors on the spectrum of a rare dermal sarcoma entity. Close clinical presentation and nearly identical histologic features but distinct prognoses make proper treatment strategies challenging. We performed a retrospective analysis of 32 patients with AFX or PDS in the scalp to provide guidance regarding the extent of radical excision to achieve stable oncological outcomes and whether radical tumor resection on the scalps required complex soft-tissue reconstruction. Compared to AFX, PDS shows a more aggressive growth pattern with frequent satellite metastases and distant metastases. These require extensive resections for local control to achieve long-term remission in most PDS patients. Despite the limited elasticity of the scalp, plastic reconstructive procedures can obtain reliable soft tissue reconstruction, even for complete scalp defects. Due to their rarity, managing these tumors requires an interdisciplinary setting in a specialized sarcoma center.

Abstract

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are two distinct designations for a rare dermal sarcoma entity. These tumors arise predominantly in the sun-damaged skin of elderly patients. Although both AFX and PDS have a similar clinical presentation and nearly identical genetic features, they significantly differ in prognosis. Here we present a retrospective single-center chart review analyzing the outcomes of patients treated for dermal sarcoma. The radicality of the tumor-resection extent and soft-tissue reconstructive options were assessed. Patients between January 2010 and August 2021 were included. We recorded resection margins, tumor recurrence, overall survival, number of operations until complete tumor resection, and reconstructive procedures; any complications were recorded. Furthermore, we analyzed a subgroup of patients with satellite metastases. A total of 32 patients met the inclusion criteria (30 male, 2 female, median age of 77.5 years (interquartile range (IQR) 74–81)). Histopathology revealed AFX in 14 patients and PDS in 18 patients. Margin-free resection was achieved in 31 cases, and 27 patients were remission free over the reported period. The local recurrence rate was 5, and distant metastasis was detected in four cases. Of all the PDS cases, nine presented with satellite metastasis. No AFX had satellite metastases. Due to their rarity, managing these tumors requires an interdisciplinary setting in a specialized sarcoma center.

Risk factors for local atypical fibroxanthoma recurrence and progression to pleomorphic dermal sarcoma: A meta-analysis of individualized participant data

Background

Risk factors for local atypical fibroxanthoma (AFX) recurrence and progression to pleomorphic dermal sarcoma (PDS) have not previously been identified.

Objective

To identify risk factors and provide follow‐up suggestions for local AFX recurrence and progression to PDS.

Methods and Materials

A literature search was performed in the PubMed, EMBASE, and Cochrane databases. The PRISMA and MOOSE guidelines were followed. The risks of local AFX recurrence and progression to PDS were presented as Kaplan–Meier plots and risk factors were presented as hazard ratios (HRs) calculated with univariate and multivariate Cox regression.

Results

Five hundred and ninety‐eight patients with AFX from 14 studies were included. Age >74 years and male sex significantly increased the risk of local recurrence (HR: 7.31 [95% confidence interval [CI]: 1.78–30.0], p < 0.01 and HR: 2.89 [95% CI: 1.04–8.01], p < 0.05, respectively). There was no difference when comparing wide local excision and Mohs' micrographic surgery (p = 0.89). The risks of local AFX recurrence and progression to PDS after 2 years were <1%.

Conclusion

A more intensive follow‐up regimen could be considered in patients >74 years old and males due to the higher risk of local AFX recurrence.

Kutane Sarkome – nicht alle sind wirklich selten, die meisten „low risk“

Die biologische und morphologische Vielfalt der Weichteilmalignome, der Sarkome, ist enorm.

Diese Übersicht fokussiert deshalb auf die 5 am häufigsten vorkommenden Weichteilmalignome. Betrachtet werden soll dabei, was der Kliniker wissen muss, was neu ist und welche Fallstricke es gibt. Ziel dieses Artikels ist es dabei, eine Übersicht zu geben sowie die Konzeptbildung darüber, womit man es im Wesentlichen zu tun hat.

Hemato-Oncological Diseases as Risk Factor for Recurrence or Metastasis of Pleomorphic Dermal Sarcoma

Background

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are increasingly common sarcomas of the skin with a genetic UV signature. Immunosuppression is a known risk factor for developing other UV-induced skin cancers such as cutaneous squamous cell carcinoma (cSCC), basal cell carcinoma (BCC), and Merkel cell carcinoma with increased mortality. In case reports or small case series of AFX/PDS patients, immunosuppression has been hypothesized as a risk factor for the development of distant metastases. The aim of the present study was to analyze immunosuppression as a risk factor for AFX/PDS in a large patient cohort.

Methods

A cohort of 164 patients with AFX/PDS (47 AFX and 117 PDS) was collected between 2003 and 2021 and analyzed for clinicopathological data with a special focus on immunosuppression.

Results

Of all patients, 29.9% had any kind of immunosuppression; 6.4% of the AFX and 12.0% of the PDS patients had underlying hemato-oncological diseases. Patients with immunosuppression due to an underlying hemato-oncological disease had a significantly increased risk of progressing to (p = 0.010) and developing distant organ metastases (p = 0.000).

Conclusions

Immunosuppression seems to be a risk factor for developing AFX/PDS with worse clinical outcomes. Therefore, immunosuppression, especially underlying hemato-oncological diseases, should be considered in the treatment and follow-up care of patients with AFX/PDS.

A Multidisciplinary Approach to Complex Dermal Sarcomas Ensures an Optimal Clinical Outcome

Primary dermal sarcomas (PDS) belong to a highly clinically, genetically and pathologically heterogeneous group of rare malignant mesenchymal tumours primarily involving the dermis or the subcutaneous tissue. The tumours are classified according to the mesenchymal tissue from which they originate: dermal connective tissue, smooth muscle or vessels. Clinically, PDS may mimic benign soft tissue lesions such as dermatofibromas, hypertrophic scarring, etc. This may cause substantial diagnostic delay. As a group, PDS most commonly comprises the following clinicopathological forms of dermal sarcomas: dermatofibrosarcoma protuberans (DFSP), atypical fibroxanthoma (AFX), dermal undifferentiated pleomorphic sarcoma (DUPS), leiomyosarcoma (LMS), and vascular sarcomas (Kaposi’s sarcoma, primary angiosarcoma, and radiation-induced angiosarcoma). This clinical entity has a broad spectrum regarding malignant potential; however, local aggressive behaviour in some forms causes surgical challenges. Preoperative, individualised surgical planning with complete free margins is pivotal along with a multidisciplinary approach and collaboration across highly specialised surgical and medical specialties. The present review gives a structured overview of the most common forms of dermal sarcomas including surgical recommendations and examples for advanced reconstructions as well as the current adjunctive medical treatment strategies. Optimal aesthetic and functional outcomes with low recurrence rates can be achieved by using a multidisciplinary approach to complex dermal sarcomas. In cases of extended local tumour invasion in dermal sarcomas, advanced reconstructive techniques can be applied, and the interdisciplinary microsurgeon should be an integral part of the sarcoma board.

S1-guideline atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS)

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare cutaneous neoplasms representing histomorphological, genetic as well as epigenetic variants of a disease spectrum. Both tumors typically manifest as nonspecific, often ulcerated, skin- to flesh-colored nodules in chronically sun-damaged skin of elderly male patients. AFX is a rather well demarcated, often rapidly growing tumor. PDS tumors are poorly circumscribed and are characterized by aggressive infiltrative growth. Fast as well as slow growth behavior has been reported for both tumors. Histologically, both are composed of spindle-shaped and epithelioid tumor cells with pleomorphic nuclei as well as atypical multinucleated giant cells. Atypical mitoses are common. In contrast to AFX, PDS involves relevant parts of the subcutis and shows areas of tumor necrosis and/or perineural infiltration. Due to the poorly differentiated nature of AFX/PDS (Grade 3), histopathologically similar cutaneous sarcomas, undifferentiated carcinomas, melanomas and other diseases have to be excluded by immunohistochemical analysis. The treatment of choice is micrographically controlled surgery. In cases of AFX, a cure can be assumed after complete excision. Local recurrence rates are low as long as PDS tumors are surgically removed with a safety margin of 2 cm. Metastasis is rare and mostly associated with very thick or incompletely excised tumors; it mainly affects the skin and lymph nodes. Distant metastasis is even more rare. No approved and effective systemic therapy has been established.

Auricular Non-Epithelial Tumors with Solar Elastosis in Cats: A Possible UV-Induced Pathogenesis

The photoinduced etiopathology of actinic keratosis and squamous cell carcinoma in feline species is well known. This etiology has also been reported for non-epithelial cutaneous tumors in other species. To date, no cases of auricular non-epithelial cutaneous neoplasms erased in a contest of actinic keratosis in cats have been reported. The aim of this study was to describe feline auricular non-epithelial cutaneous neoplasms associated with typical UV-induced cutaneous lesions and solar elastosis. The study was conducted on five feline cases diagnosed with auricular non-epithelial cutaneous tumors (two fibrosarcomas, one mixosarcoma, one epithelioid melanoma and one hemangiosarcoma), selected from the Tumor Registry of the Department of Veterinary Sciences of the University of Pisa (1998–2018). Ten and six feline auricular biopsies of normal skin and skin with actinic keratosis, respectively, were used as controls. Orcein stain was used to investigate solar elastosis. Histological changes related to chronic solar irradiation were documented in the skin adjacent to the neoplastic lesions in the five cats. Considering the anatomical localization and the results of histopathology, this study suggests that non-epithelial cutaneous neoplasms may have a UV-induced etiopathogenesis in the feline species.

Pleomorphic dermal sarcoma: Clinicopathological features and outcomes from a 5-year tertiary referral centre experience

BACKGROUND

Pleomorphic dermal sarcoma (PDS) describes rare dermal-based malignant tumours that are morphologically similar to atypical fibroxanthoma (AFX). PDS may be differentiated from AFX by the presence of one or more of the following histologic features: subcutaneous invasion, tumour necrosis, lymphovascular invasion (LVI), and/or perineural infiltration (PNI).

AIMS

To further define the clinicopathological features, surgical management, and outcomes of PDS primary tumours.

METHODS AND RESULTS

This study was a retrospective observational case series using a database search from 2012 to 2017. Inclusion criteria required all cases to meet the histopathologic criteria for PDS as confirmed by a specialist soft-tissue histopathologist. A total of n = 17 cases were included with a median age of 78 years (range 66-85). All tumours were located on the head and neck, with 13/17 located on the scalp. Primary treatment was with wide local excision (WLE) in all cases. Median follow-up was 48 months. Local recurrence occurred in 4/17 cases (24%) and distant metastasis in 2/17 cases (12%).

CONCLUSION

PDS behaves more aggressively than atypical fibroxanthoma with which it shares a biologic continuum. The optimal surgical management approach is yet to be determined.

Immunohistochemical ALK Expression in Granular Cell Atypical Fibroxanthoma: A Diagnostic Pitfall for ALK-Rearranged Non-neural Granular Cell Tumor

ABSTRACT

Atypical fibroxanthoma (AFX) is a neoplasm that most commonly occurs on sun-damaged skin of the head and neck in elderly patients and that usually exhibits indolent clinical behavior with complete excision. The granular cell variant of AFX demonstrates overlapping histopathologic features with dermal non-neural granular cell tumor (NNGCT), which typically arises on the extremities of young to middle aged adults with rare reports of regional metastasis. A subset of NNGCT harbors ALK rearrangements and expresses ALK by immunohistochemistry. Here, we present 2 cases of granular cell AFX occurring on the scalp of males aged 73 and 87 with ALK expression by immunohistochemistry and no evidence of an ALK rearrangement on fluorescence in situ hybridization, representing a diagnostic pitfall for NNGCT.

The clinicopathologic spectrum and genomic landscape of de-/trans-differentiated melanoma

Dedifferentiation and transdifferentiation are rare and only poorly understood phenomena in cutaneous melanoma. To study this disease more comprehensively we have retrieved 11 primary cutaneous melanomas from our pathology archives showing biphasic features characterized by a conventional melanoma and additional areas of de-/trans-differentiation as defined by a lack of immunohistochemical expression of all conventional melanocytic markers (S-100 protein, SOX10, Melan-A, and HMB-45). The clinical, histologic, and immunohistochemical findings were recorded and follow-up was obtained. The patients were mostly elderly (median: 81 years; range: 42-86 years) without significant gender predilection, and the sun-exposed skin of the head and neck area was most commonly affected. The tumors were deeply invasive with a mean depth of 7 mm (range: 4-80 mm). The dedifferentiated component showed atypical fibroxanthoma-like features in the majority of cases (7), while additional rhabdomyosarcomatous and epithelial transdifferentiation was noted histologically and/or immunohistochemically in two tumors each. The background conventional melanoma component was of desmoplastic (4), superficial spreading (3), nodular (2), lentigo maligna (1), or spindle cell (1) types. For the seven patients with available follow-up data (median follow-up period of 25 months; range: 8-36 months), two died from their disease, and three developed metastases. Next-generation sequencing of the cohort revealed somatic mutations of established melanoma drivers including mainly NF1 mutations (5) in the conventional component, which was also detected in the corresponding de-/trans-differentiated component. In summary, the diagnosis of primary cutaneous de-/trans-differentiated melanoma is challenging and depends on the morphologic identification of conventional melanoma. Molecular analysis is diagnostically helpful as the mutated gene profile is shared between the conventional and de-/trans-differentiated components. Importantly, de-/trans-differentiation does not appear to confer a more aggressive behavior.

Undifferentiated and dedifferentiated soft tissue neoplasms: Immunohistochemical surrogates for differential diagnosis

Undifferentiated soft tissue sarcomas (USTS) are described in the current World Health Organization Classification of Soft Tissue and Bone Tumours as those showing no identifiable line of differentiation when analyzed by presently available technologies. This is a markedly heterogeneous group, and the diagnosis of USTS remains one of exclusion. USTS can be divided into four morphologic subgroups: pleomorphic, spindle cell, round cell and epithelioid undifferentiated sarcomas, with this combined group accounting for up to 20% of all soft tissue sarcomas. As molecular advances enable the stratification of emerging genetic subsets within USTS, particularly within undifferentiated round cell sarcomas, other groups, particularly the category of undifferentiated pleomorphic sarcomas (UPS), still remain difficult to substratify and represent heterogeneous collections of neoplasms often representing the common morphologic endpoints of a variety of malignant tumors of various (mesenchymal and non-mesenchymal) lineages. However, recent molecular developments have also enabled the identification and correct classification of many tumors from various lines of differentiation that would previously have been bracketed under 'UPS'. This includes pleomorphic neoplasms and dedifferentiated neoplasms (the latter typically manifesting with an undifferentiated pleomorphic morphology) of mesenchymal (e.g. solitary fibrous tumor and gastrointestinal stromal tumor) and non-mesenchymal (e.g. melanoma and carcinoma) origin. The precise categorization of 'pleomorphic' or 'undifferentiated' neoplasms is critical for prognostication, as, for example, dedifferentiated liposarcoma typically behaves less aggressively than other pleomorphic sarcomas, and for management, including the potential for targeted therapies based on underlying recurrent molecular features. In this review we focus on undifferentiated and dedifferentiated pleomorphic and spindle cell neoplasms, summarizing their key genetic, morphologic and immunophenotypic features in the routine diagnostic setting, and the use of immunohistochemistry in their principal differential diagnosis, and highlight new developments and entities in the group of undifferentiated and dedifferentiated soft tissue sarcomas.