Atypical fibroxanthoma: a selective review

Superficial CD34+ fibroblastic tumor with focal atypical presentation: A case report

Superficial CD34+ fibroblastic tumors (SCPFTs) are rare mesenchymal tumors with distinct morphological features. Although several cases of SCPFT have been reported, a comprehensive understanding of its clinical and biological features necessitates the inclusion of additional cases. The current study presents a case of SCPFT, where morphological observations, immunohistochemical staining and fluorescence in situ hybridization (FISH) were performed. Immunohistochemistry revealed diffuse CD34 expression and integrase interactor 1 expression, whilst FISH indicated rearrangement of the PR/SET domain 10 gene. Microscopic assessment demonstrated typical SCPFT pathology, with a focal nodular region showing a high Ki-67 index, suggesting heterogeneity and the potential for local recurrence. The present study also briefly reviews the differential diagnosis of tumors with morphological similarities. It was found that the precise diagnosis of SCPFT relies on the distinctive pathological features, the use of immunohistochemical markers, including CD34 staining, and the differentiation from similar histological lesions.

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.

Cutaneous Atypical Fibroxanthoma With Osteoclast-Like Giant Cell: A Rare but Diagnostic Pitfall

BACKGROUND

Atypical fibroxanthoma (AFX) is a dermal-based, low-grade neoplasm with no specific lineage of differentiation. The occurrence of AFX with osteoclast-like giant cells is exceptionally rare. Less than 20 cases have been reported in the literature.

CASE PRESENTATION

A 77-year-old man with a medical history of multiple basal and squamous cell carcinomas of the skin, presented with a progressively growing erythematous nodule on the sun-damaged right central parietal scalp. A shave biopsy showed a dermal spindle cell proliferation accompanied by numerous osteoclast-like multinucleated giant cells and predominant atypical mitotic figures. The immunohistochemical staining showed a diffuse positive staining for CD68 and SMA, patchy staining for CD10, and negative staining for SOX-10, pan-cytokeratin, CK5/6, S100, CD34, and desmin. The tumor was completely excised with negative margins. A subsequent follow-up over a period of 13 months showed no recurrence.

CONCLUSION

Distinguishing AFX with osteoclast-like giant cells from both malignant and benign skin lesions with osteoclast-like giant cells is crucial. Although AFX tumors display worrisome malignant histologic features, most cases have a favorable prognosis with a local recurrence rate below 5% and exceedingly rare metastasis.

[Atypical fibroxanthoma]

Atypical fibroxanthoma (AFX) is a rare skin tumor characterized by a combination of a «malignant» morphological features and non-aggressive clinical course. Diagnosing AFX is challenging due to histological «diversity» and heterogeneous immunophenotype. The presented review describes the history and evolution of AFX as a nosological form of cancer, its histogenetic origin, pathogenesis and biological potential. The clinical, morphological, immunohistochemical, molecular cytogenetic characteristics and histological subtypes of the tumor as well as differential diagnosis have been presented in detail.

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.

Cutaneous atypical fibroxanthoma with osteoclast-like giant cell: a rare phenomenon

Atypical fibroxanthoma with osteoclast-like giant cells is a rare entity. We present the case of an elderly woman who presented with a pink-purple dome-shaped nodule with central hyperkeratotic crust. Biopsy revealed a cellular, dermal based tumor comprised of spindle, oval, and osteoclast-like giant cells with pleomorphism. The immunohistochemistry profile supported a diagnosis of atypical fibroxanthoma (AFX) with osteoclast-like giant cells. We performed a literature review through PubMed and Google Scholar for AFX with osteoclast-like giant cell formation and found 16 previously reported cases. We aim to provide a review and discuss features of these cases. We also discuss the pathogenesis of these osteoclast-like cells as well as potential pitfalls in diagnosis. This article is protected by copyright. All rights reserved.

An Unusual Case of Desmoplastic Melanoma With Monster Cells Imitating an Atypical Fibroxanthoma

Numerous cells with very large and irregular nuclei ("monster" cells) have not hitherto been reported in desmoplastic melanoma (DM). Their prognostic significance in melanomas is a matter of debate, although some authors have associated them with more aggressive tumor behavior. We report a mixed DM on the scalp of an 88-year-old woman imitating an atypical fibroxanthoma. Tumor cells stained positive for SOX10, S100, and cyclin D1; BRAF mutation status was negative, and fluorescence in situ hybridization analysis showed copy number gains in 11q13 (cyclin D1) and 6p25 (RREB1), and loss in 6q23 (MYB). Cyclin D1 amplification is associated with poor prognosis in melanoma.

Pleomorphic dermal sarcoma: a clinical and histological review of 49 cases

Pleomorphic dermal sarcoma (PDS) is a rare mesenchymal neoplasm that shares histopathological features with atypical fibroxanthoma (AFX), but has additional features of deep invasion of the superficial subcutis, tumour necrosis, and vascular and perineural invasion, which confers a risk of local recurrence and metastases. To study the clinical and pathological spectrum more comprehensively, we retrieved 49 cases of pleomorphic dermal sarcoma from our departmental files. There was a strong male predominance (n=45). The mean (range) age at presentation was 80 (47-97) years. The tumours had a median (range) maximum dimension of 23.5 (5-75) mm. There was a strong predilection for the head and face (n=47), with the scalp (n=32) being the most common site. Ulceration was observed in 21 patients, tumour necrosis in seven, perineural infiltration in six, and lymphovascular invasion in two. CD10 was expressed in all cases. Smooth muscle actin was expressed in 15 and CD68 in 14. Follow up was available in 41 cases (mean (range) 22.4 (2-90) months). Six patients had local recurrences, despite all having originally undergone primary surgical resections and having reports of clear margins. Progressive metastatic disease was observed in one patient who died from their disease. Based on the Kaplan Meier method, median overall survival was 70.8 (8.4-133.1) months. Although AFX and PDS may be part of a spectrum, distinction is important to emphasise the potential for malignant behaviour in PDS.

A genomic survey of sarcomas on sun-exposed skin reveals distinctive candidate drivers and potentially targetable mutations

Sarcomas on photodamaged skin vary in prognosis and management, but can display overlapping microscopic and immunophenotypic features. Improved understanding of molecular alterations in these tumors may provide diagnostic and therapeutic insights. We characterized 111 cutaneous sarcomatoid malignancies and their counterparts, including primary cutaneous angiosarcoma (n = 7), atypical fibroxanthoma (AFX) (n = 21), pleomorphic dermal sarcoma (PDS) (n = 17), extracutaneous undifferentiated pleomorphic sarcoma (n = 8), cutaneous leiomyosarcoma (LMS) (n = 5), extracutaneous LMS (n = 9), sarcomatoid squamous cell carcinoma (spindle cell squamous cell carcinoma) (S-SCC) (n = 24), and conventional cutaneous squamous cell carcinoma (SCC) (n = 20), by next-generation sequencing (NGS) using the StrataNGS panel for copy number variations, mutations, and/or fusions in more than 60 cancer-related genes. TP53 mutations were highly recurrent in most groups. Angiosarcoma displayed previously reported MYC amplifications, as well as CCND1 gains. RB1 mutations were relatively restricted to cutaneous LMS. As previously reported, PIK3CA mutations occurred in AFX, whereas RAS activation was more frequent in PDS. CDKN2A mutations were recurrent in AFX and S-SCC, whereas PDS displayed frequent CDKN2A deletion. S-SCC displayed mutational similarity to conventional SCC. BRCA1/2 mutations were specific to tumors with disease progression. In a subset, we detected potential driver events novel to these tumor types: activating mutations in IDH2 (PDS), MAP2K1 (angiosarcoma, PDS), and JAK1 (S-SCC) and copy gains in FGFR1 (angiosarcoma, S-SCC), KIT (AFX), MET (PDS), and PDGFRA (PDS). Our findings confirm and expand the spectrum of known genomic aberrations, including potential targetable drivers, in cutaneous sarcomatoid malignancies. In addition, certain events are relatively specific to particular tumors within this differential diagnosis and hence might be diagnostically informative.

Superficial CD34 positive fibroblastic tumor: report of three cases and review of the literature

Superficial CD34 positive fibroblastic tumor (SCPFT) is a recently recognized, unique neoplasm with distinctive histomorphological features such as high pleomorphism, low mitotic rate, and diffuse CD34 reactivity. Hereby we present three cases of our experience with clinicopathological, morphological, and immunohistochemical characteristics. The patients were a 31-year-old female, 53-year-old female, and 33-year-old male. The tumors were all superficially located; left forearm, medial aspect of the left ankle, and left thigh, respectively. Histomorphologically they had expansile and focal infiltrative growth pattern consisting of highly pleomorphic spindle cells with intranuclear inclusions, yet low mitotic rate. Tumoral cells showed strong and diffuse reactivity for CD34. One of our cases showed focal and weak reactivity for pancytokeratin. Unlike the other two tumors, one case was positive for desmin. During the clinical follow-up, one case showed local recurrence four times. SCPFT is a newly recognized, borderline mesenchymal neoplasm of soft tissues that can show local recurrence or even rarely metastasize. To the best of our knowledge, this three case series is the first to be reported from Turkey. Our aim to report these three cases was to make contribution to the literature about this rare entity and increase awareness.

Cutaneous Spindle Cell Neoplasms: Pattern-Based Diagnostic Approach

Context.—

Spindle cell neoplasms arising in the skin comprise a heterogeneous group of tumors with divergent lineages. Cutaneous spindle cell neoplasms are relatively common and present surgical pathologists with diagnostic challenges. Recognition of their histopathologies is important for correct diagnosis and management. The current review presents a pattern-based diagnostic approach to common cutaneous spindle cell neoplasms that often cause diagnostic difficulties.

Objective.—

To provide a useful guide for diagnosis of cutaneous spindle cell neoplasms.

Data Sources.—

PubMed (US National Library of Medicine) reports and the authors' personal experiences are reviewed.

Conclusions.—

The authors briefly summarize the histologic features and differential diagnoses of common cutaneous spindle cell neoplasms.

Pleomorphic Dermal Sarcoma of the Scalp

Pleomorphic dermal sarcoma (PDS) is a rare mesenchymal tissue tumor. Distinguishing PDS from similar conditions, such as atypical fibroxanthoma (AFX), its less aggressive tumor counterpart, is difficult, as they are clinically and histologically similar. We present a case of a 77-year-old man presenting with a large nodular scalp lesion of three weeks duration. Pathology revealed a 3.3 cm invasive pleomorphic dermal sarcoma. Surgical excision with 2 cm margins was performed with successful healing of the graft. This case highlights a rare case of a large pleomorphic dermal sarcoma and discusses the histological features and management of PDS.

Cutaneous Smooth Muscle Tumors: A Review

Smooth muscle tumors occur infrequently in the skin. They consist of a diverse group of lesions representing hamartomas as well as benign and malignant neoplasms. They may arise from arrector pili muscle, specialized smooth muscle of the genitalia, or vascular smooth muscle. Although rare, accurate diagnosis and classification of cutaneous smooth muscle proliferations is important as they can exhibit a range of clinical behavior and may be associated with underlying syndromes. This review summarizes the clinicopathologic spectrum of smooth muscle tumors involving the skin.

Atypical fibroxanthoma and pleomorphic dermal sarcoma harbor frequent NOTCH1/2 and FAT1 mutations and similar DNA copy number alteration profiles

Atypical fibroxanthomas and pleomorphic dermal sarcomas are tumors arising in sun-damaged skin of elderly patients. They have differing prognoses and are currently distinguished using histological criteria, such as invasion of deeper tissue structures, necrosis and lymphovascular or perineural invasion. To investigate the as-yet poorly understood genetics of these tumors, 41 atypical fibroxanthomas and 40 pleomorphic dermal sarcomas were subjected to targeted next-generation sequencing approaches as well as DNA copy number analysis by comparative genomic hybridization. In an analysis of the entire coding region of 341 oncogenes and tumor suppressor genes in 13 atypical fibroxanthomas using an established hybridization-based next-generation sequencing approach, we found that these tumors harbor a large number of mutations. Gene alterations were identified in more than half of the analyzed samples in FAT1, NOTCH1/2, CDKN2A, TP53, and the TERT promoter. The presence of these alterations was verified in 26 atypical fibroxanthoma and 35 pleomorphic dermal sarcoma samples by targeted amplicon-based next-generation sequencing. Similar mutation profiles in FAT1, NOTCH1/2, CDKN2A, TP53, and the TERT promoter were identified in both atypical fibroxanthoma and pleomorphic dermal sarcoma. Activating RAS mutations (G12 and G13) identified in 3 pleomorphic dermal sarcoma were not found in atypical fibroxanthoma. Comprehensive DNA copy number analysis demonstrated a wide array of different copy number gains and losses, with similar profiles in atypical fibroxanthoma and pleomorphic dermal sarcoma. In summary, atypical fibroxanthoma and pleomorphic dermal sarcoma are highly mutated tumors with recurrent mutations in FAT1, NOTCH1/2, CDKN2A, TP53, and the TERT promoter, and a range of DNA copy number alterations. These findings suggest that atypical fibroxanthomas and pleomorphic dermal sarcomas are genetically related, potentially representing two ends of a common tumor spectrum and distinguishing these entities is at present still best performed using histological criteria.

Oncogene and therapeutic target analyses in atypical fibroxanthomas and pleomorphic dermal sarcomas

BACKGROUND

Until 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 METHODS

We performed the world-wide most comprehensive immunohistochemical and mutational analysis in well-defined AFX (n=5) and PDS (n=5).

RESULTS

In 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.

CONCLUSIONS

UV-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.

Cutaneous/subcutaneous mesenchymal proliferations of the breast

Cutaneous mesenchymal "spindle cell" lesions arising in the vicinity of the breast represent a complex clinical and diagnostic scenario which may overlap histopathologically and immunohistochemically with mammary spindle cell proliferations, potentially impacting management and overall prognostication. In this review, we suggest a pattern-based approach to assist in the evaluation of these lesions. A comprehensive description of each entity is accompanied by a cutaneous and mammary differential diagnosis.

Superficial CD34-positive fibroblastic tumour: a clinicopathological and immunohistochemical study of an additional series

AIMS

To describe an additional series of superficial CD34-positive fibroblastic tumour, a newly described neoplasm, in order to enhance the recognition of an emerging novel entity.

METHODS AND RESULTS

The clinicopathological features and immunophenotypes of 11 cases of superficial CD34-positive fibroblastic tumour were studied. There were eight males and three females, with a median age of 36 years. Tumours occurred in the thigh (n = 4), buttock (n = 3), shoulder (n = 2), upper arm (n = 1), and waist (n = 1). Histologically, all tumours were characterized by relative circumscription, pleomorphic spindled to polygonal cells with variably enlarged bizarre-appearing cells, intranuclear cytoplasmic pseudoinclusions, and extremely low mitotic activity. Immunohistochemically, neoplastic cells showed diffuse and strong expression of CD34 and focal staining of cytokeratin. Follow-up thus far has revealed an indolent clinical behaviour.

CONCLUSIONS

Superficial CD34-positive fibroblastic tumour represents a new member of the family of cutaneous CD34-positive spindle-cell tumours. Familiarity with its clinicopathological characteristics is helpful in avoiding confusion with a variety of cutaneous mesenchymal tumours with overlapping features.

Clear cell atypical fibroxanthoma: a case report and review of the literature

Atypical fibroxanthoma (AFX) is a group of cutaneous tumors characterized by a population of fusiform, epithelioid and pleomorphic cells. Clinically, AFX is commonly found on the head and neck of older adults as a solitary ulcerated nodule. Clear cell atypical fibroxanthoma is a very rare variant of AFX, with only 13 cases reported to date. The differential diagnoses often include dermal neoplasms composed of clear cells, such as squamous cell carcinoma, basal cell carcinoma, metastatic renal cell carcinoma and balloon cell malignant melanoma. These diagnoses can be ruled out by the typical immunohistochemical profile of clear cell AFX, which is negative for specific epithelial and melanocytic markers. Herein, we describe a rare and unusual case of clear cell AFX arising on the ear of a relatively young adult patient. Histologically, the dermis was completely replaced by an atypical population of vacuolated cells with numerous atypical mitoses. Immunohistochemical stains were negative forpancytokeratin, CK5/6, CK7, and p63 S100 and Melan-A stains. CD10 and CD68 stains were positive, making the findings consistent with the diagnosis of clear cell atypical fibroxanthoma.

An open label pilot study of supraerythemogenic excimer laser in combination with clobetasol spray and calcitriol ointment for the treatment of generalized plaque psoriasis

A common therapeutic modality for psoriasis includes the combination of phototherapy with topical treatments. The recent development of targeted phototherapy with the excimer laser and spray formulations for topical treatments has increased the efficacy and convenience of these combinational therapies. Herein, we aim to assess the efficacy of a novel combination of therapies using the 308 nm excimer laser, clobetasol propionate spray and calcitriol ointment for the treatment of moderate to severe generalized psoriasis. In this 12-week study, patients with moderate to severe psoriasis received twice weekly treatments with a 308-nm excimer laser combined with clobetasol proprionate twice daily for a month followed by calcitriol ointment twice daily for the next month. Of the 30 patients enrolled, 83% of patients (25/30) achieved PASI-75 [65-94%, 95% confidence interval (CI)] at week 12. For PGA, there was an estimated decrease of 3.6 points (3.1-4.1, 95% CI, p < 0.0005) by week 12. In conclusion, the combination of excimer laser with alternating clobetasol and calcitriol application has shown to be a promising combination of therapies for the treatment of moderate to severe generalized psoriasis. Further evaluation may be conducted with a larger study inclusive of control groups and head-to-head comparisons against topical steroid and UVB therapy as monotherapies.

Pleomorphic spindle cell dermal neoplasm with dot-like keratin reactivity: keratin-positive AFX or carcinoma?

Atypical fibroxanthoma (AFX) is an uncommon cutaneous neoplasm of pleomorphic myofibroblast-like cells. Diagnosis requires exclusion of other undifferentiated spindle and pleomorphic cell neoplasms by immunohistochemistry. We report two patients with p63-non-reactive spindle cell neoplasms which resembled AFX but demonstrated anomalous dot-like immunolabeling with antibodies to high molecular weight keratin and keratin 5. One case recurred locally, suggesting such lesions may behave aggressively. Whether these lesions represent keratin-positive dermal sarcomas or poorly differentiated carcinomas is debatable. Regardless of exact classification, our experience suggests such cases should be managed as high-risk non-melanoma skin cancers.

Atypical Fibroxanthoma: A case series and review of literature

INTRO/OBJECTIVE

Atypical Fibroxanthoma (AFX) is a rare cutaneous neoplasm arising from myofibroblast or fibroblast-like cells that predominantly affects the head and neck region. It commonly mimics more invasive neoplasms and is a diagnostic challenge to clinicians. The aim of this study was to develop a better understanding of AFX, focusing on recent developments in diagnosis and management.

METHODS

A retrospective case series and review of recent literature were carried out.

RESULTS

Over a 17-year period, seven cases were identified (six male, mean age at presentation was 75.9 years). Two patients underwent complete excision and five patients had curettage and cauterisation. Two patients developed local recurrence but none demonstrated signs suggestive of metastatic spread. Histologically all seven lesions displayed a spindle cell pattern. Where performed, immunohistochemical staining was positive for Vimentin, CD10, CD68 and actin, and negative for CAM 5.2, CD34, Melan-A, S100 protein, HMB45, Cytokeratin A1/A3.

CONCLUSION

Our patient demographics, histopathology and immunohistochemistry are comparable to previous studies. Although advances have been made in immunohistochemical analysis, we are yet to discover a specific diagnostic immunostain for AFX. Clinical findings should therefore be correlated with histology and a panel of immunohistochemical stains should be used. Given the potential for recurrence or metastases, Moh's Micrographic Surgery with regular follow-up may be the preferred management.

Atypical fibroxanthoma†

Atypical fibroxanthoma (AFX) is a rare skin neoplasm of low-grade malignancy and fibroblastic origin. AFX is a curable cutaneous disease and the diagnosis depends on knowledge of its clinical and histological features and combined immunohistochemistry markers. This study presents a case of a male patient, aged 90 years, presented with painless skin lesion in his ear. The lesion had been growing progressively for 2 months, measured ∼1.5 cm, ulcerated, fixed and firm. After a biopsy, the patient underwent a complete resection with adequate surgical margins and showed favorable evolution without complications or recurrence. The histopathological evaluation showed a poorly circumscribed ulcerated dermal nodule, mesenchymal proliferation, with pleomorphic spindle cells. There was infiltration of the deep dermis and subcutis, showing malignant features, but there was no invasion of cartilage. The immunohistochemical analysis confirmed the diagnosis of AFX.

[Atypical fibroxanthoma of the scalp: overview and recent developments]

Atypical fibroxanthoma (AFX) is a rare, low-malignant, mesenchymal tumor of the dermis and is assigned to the group of fibrohistiocytic tumors. The tumor occurs especially in photodamaged skin on the scalp of elderly men. A clinical diagnosis is not possible due to a multitude of possible differential diagnoses (leiomyosarcoma, squamous cell carcinoma, spindle cell malignant melanoma, dermatofibrosarcoma protuberans). Immunohistochemical and histological examinations should be performed to confirm the diagnosis. The tumor shows a very good prognosis after complete excision. Micrographically controlled surgery is considered as the treatment of choice.

Sarcoma-like tumor of head and neck skin

A group of tumors referred to as atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) predominantly occur in sun-damaged skin of the elderly, particularly in the head and neck region. Although this group of tumors is often regarded as of mesenchymal phenotype, the matter of histogenesis has not been entirely resolved. Evans H and Smith JL reported in 1980 that prognosis was not significantly different irrespective of whether there was a definite squamous cell carcinoma component or not, supporting a view that these are all carcinomata in nature (sarcomatoid carcinoma [SC]). There are a number of clinicopathologic studies of AFX in the literature but information on morphologically similar sarcoma-like tumors with immunohistochemical evidence of epithelial differentiation is sparse. One hundred sarcoma-like tumors (SLTs) of head and neck skin of the elderly, treated by surgical excision, were studied. Clinical information was obtained, and pathology reports and hematoxylin and eosin sections were reviewed to document size (maximum dimension), extent of invasion, mitotic count, vascular and perineural invasion, margin status, ulceration, necrosis, and the presence of actinic keratosis in adjacent/overlying skin. Immunostains examined included: pan-cytokeratins (CKs) (AE1/AE3, MNF116), high-molecular weight CKs (34βE12, CK5/6, CK14), p63, and melanocytic (S100, Melan A, HMB-45, MITF), vascular (CD31, CD34), and muscle markers (SMA, desmin, h-caldesmon) to exclude melanoma and definite sarcoma entities. The tumors were divided into AFX/PDS (G1), the SC group, which was subdivided into SLT with only p63 positivity (G2a) and SLT with CK positivity regardless of p63 status (G2b), and SLT with a minor morphologic squamous cell carcinoma component (G3). Clinicopathologic findings of each group were compared, in relation to outcomes. Age at diagnosis ranged from 51 to 96 years (median, 79 y), with M:F=11.5:1. There were 53 tumors in G1 (19AFX, 34PDS), 37 in G2 (25 in G2a, 12 in G2b), and 10 in G3. There was no statistically significant difference in clinical and pathologic parameters or survival among all 3 groups. CKs and p63 expression, size, extent of invasion, vascular invasion, perineural invasion, mitotic count, and ulcer did not affect outcome, whereas margin status and necrosis did by both univariate and multivariate analysis and by only univariate analysis, respectively. Sixty patients had multiple nonmelanomatous skin cancers. Actinic keratosis was observed in overlying/adjacent epidermis in 51 cases. Eight patients had prior radiotherapy to head skin cancers; 1 patient developed 2 separate tumors (G1 and G3) after radiotherapy. Four patients died of tumor (1 G1, 2 G2b, and 1 G3); of these, 3 cases had positive margin, and 1 had narrow margin. Our results have shown similarities of various clinicopathologic parameters between AFX/PDS and SC, raising the possibility that both entities are related, and some of the former entities may represent complete dedifferentiation (complete loss of epithelial phenotype) with a gain of mesenchymal phenotype. In addition, the difference between AFX and PDS appears to be the extent of invasiveness (stage) rather than a different histogenesis. Further investigations are needed. However, from a practical point of view, efforts should be made to excise this group of tumors with clear margins, as margin status appears to be the most important prognostic factor regardless of the presence or absence of epithelial differentiation.

Atypical fibroxanthoma: new insights

Atypical fibroxanthoma (AFX) is an ultraviolet radiation-associated dermal neoplasm. To address the clinicopathologic and molecular features of this particular neoplasm. The author conducted a literature review using PubMed searching for articles relating to AFX. AFX usually appears as a rapidly growing nodular or nodulo-ulcerative lesion. It occurs on sun-exposed skin of elderly peoples. AFX may be composed predominantly of pleomorphic, spindle, epithelioid cells, or admixture of these cells. The differential diagnosis of AFX includes pleomorphic dermal sarcoma, squamous cell carcinoma, malignant melanoma and leiomyosarcoma. Several observations favor a mesenchymal origin for AFX. These reviews address the clinicopathologic features, molecular pathology, prognosis and treatment of this neoplasm.

Clear cell atypical fibroxantoma: a rare variant of atypical fibroxanthoma and review of the literature

Atypical fibroxanthoma (AFX) is a superficial variant of pleomorphic malignant fibrous histiocytoma. Clear cell atypical fibroxanthoma (CCAFXA) is a rare variant of atypical fibroxanthoma. A 74-year-old male patient presented with a rapidly growing nodule on the shoulder, which had appeared over a 5-months period. Lesion was excised by the plastic surgeon. Microscopic examination showed an ulcerated nodule composed of pleomorphic spindled and polygonal cells with clear or vacuolated cytoplasm. The neoplastic cells were stained positively with CD68 and CD10 and were stained negative with S-100, Melan A, muscle-specific actin, or pan-cytokeratin. Final diagnosis was clear cell atypical fibroxanthoma. CCAFXA should be differentiated from other clear-cell neoplasms of the skin. Best of our knowledge only 11 cases CCAFXA of have been reported in published studies till date. Herein, we reported 12th case in literature of CCAFXA and review of the literature.

TERT promoter mutations are frequent in atypical fibroxanthomas and pleomorphic dermal sarcomas

Activating mutations in the TERT promoter leading to increased telomerase expression were recently identified in cutaneous melanoma and subsequently in many other types of cancer. These mutations lead to increased telomerase expression, allowing cells to proliferate continuously without entering apoptosis or senescence. Atypical fibroxanthomas and pleomorphic dermal sarcomas are genetically poorly understood tumors developing in the skin of older patients. Known genetic events in these tumors are mutations in TP53 (atypical fibroxanthoma and pleomorphic dermal sarcoma) and RAS (pleomorphic dermal sarcoma) genes, often having a UV signature. We analyzed a cohort of 27 atypical fibroxanthomas and 34 pleomorphic dermal sarcomas for the presence of TERT promoter mutations by conventional Sanger sequencing. TERT promoter mutations were identified in 25 (93%) atypical fibroxanthomas and in 26 (76%) pleomorphic dermal sarcomas. Mutations were found to have a UV signature (C>T or CC>TT) and were largely identical to those detected in cutaneous melanoma. Our data show that TERT promoter mutations are the most frequent mutations in atypical fibroxanthomas and pleomorphic dermal sarcomas reported to date. The identified mutations confirm the pathogenetic role of UV exposure in both atypical fibroxanthomas and pleomorphic dermal sarcomas and suggest that telomere maintenance through increased expression of telomerase plays an important role in the pathogenesis of these tumors.