Cytokeratin-positive Malignant Tumor in the Abdomen With EWSR1/FUS-CREB Fusion: A Clinicopathologic Study of 8 Cases.

ATF1, CREB1, and CREM, which encode the CREB family of transcription factors, are fused with EWSR1 or FUS in human neoplasms, such as angiomatoid fibrous histiocytoma. EWSR1/FUS-CREB fusions have recently been reported in a group of malignant epithelioid tumors with a predilection to the peritoneal cavity and frequent cytokeratin expression. Here, we studied 8 cytokeratin-positive abdominal malignancies with these fusions for further characterization. The tumors affected males (15 to 76 y old) and presented as intra-abdominal masses with concurrent or subsequent peritoneal dissemination, ascites, and/or metastases to the liver or lymph nodes. Four patients died of the disease within 18 to 140 months. Cases 1 to 5 showed multinodular growth of monomorphic epithelioid cells with focal serous cysts. Lymphoplasmacytic infiltration was prominent and was associated with systemic inflammatory symptoms. Two patients suffered from membranous nephropathy with nephrosis. The tumors displayed partly overlapping phenotypes with malignant mesothelioma, including diffuse strong expression of AE1/AE3 and WT1 and membranous positivity of sialylated HEG1, although calretinin was negative. Case 6 showed similar histology to cases 1 to 5, but expressed smooth muscle actin diffusely, lacked WT1 and HEG1, and harbored prominent pseudoangiomatous spaces. Cases 7 and 8 displayed dense growth of small oval to short spindle cells, with occasional molding and minor swirling, superficially resembling small cell carcinoma. Lymphoplasmacytic infiltration was not observed. The tumors were positive for AE1/AE3 and CD34 (focal), whereas calretinin, WT1, and HEG1 were negative. The detected fusions were FUS-CREM (n=4), EWSR1-ATF1 (n=2), EWSR1-CREB1 (n=1), and EWSR1-CREM (n=1). We confirmed the prior observation that these tumors do not fit perfectly with known entities and provided additional novel clinicopathologic information. The tumors require wider recognition because of more aggressive behavior than angiomatoid fibrous histiocytoma despite similar genetics, and potential misdiagnosis as unrelated diseases, such as neuroendocrine neoplasms.

Fibrous histiocytoma/dermatofibroma in children: the same as adults?

Fibrous histiocytoma (FH) or dermatofibroma is a common cutaneous lesion mostly seen in adults and rare in the first two years of life. Two hundred sixty-seven patients younger than 18 years with a diagnosis of FH or dermatomyofibroma, a lesion with morphologic overlap with FH, were identified from the files of a single institution, with only 13 (4.8%) occurring in patients younger than 5 years. Ten patients had either underlying neurologic, autoimmune, or metabolic disorders or a family history of autoimmune conditions. Histologic review of hematoxylin and eosin staining and immunostaining on 75 FHs and dermatomyofibroma in 70 patients showed the following results: 33 classic FHs, 8 classic FHs characterized by a peculiar retiform morphology with thin fascicles of elongated cells forming a network reminiscent of the eruptive variant of FH, 19 deep/cellular variants, 5 aneurysmal variants, 3 lipidized variants (including two lesions in a patient affected by mucopolysaccharidosis IV), 3 dermatomyofibromas, and 4 isolated cases of hemosiderotic, granular cell atypical, and epithelioid FH. Immunostaining for factor XIIIa highlighted a dense network of dendritic cells in FH, which was significantly reduced in the FH with retiform morphology. Smooth muscle actin staining was positive in a high percentage of FHs (85.3%). The current series demonstrates that FH in children may show unique clinical and morphologic features. The retiform pattern with decreased dendritic cells found in congenital lesions and in two older patients with lesions in two locations might have a different pathogenesis, probably related to an altered immune response in very young patients.

Cutaneous soft tissue tumors: diagnostically disorienting epithelioid tumors that are not epithelial, and other perplexing mesenchymal lesions.

Cutaneous soft tissue tumors with epithelioid features present a diagnostic challenge given that many entities in this category are rare, and they show morphologic overlap with significantly more common cutaneous epithelial and melanocytic neoplasms. The challenge is compounded by overlapping expression of epithelial or melanocytic markers in some of these entities. A broad spectrum of primary cutaneous epithelioid soft tissue tumors exists, including benign and malignant counterparts of tumors with various differentiation including melanocytic, peripheral nerve sheath, angiomatous, fibrohistiocytic, and myoid or myoepithelial, in addition to translocation-associated tumors lacking a derivative tissue type. Given this spectrum, an initial targeted immunohistochemical panel for epithelioid dermal and subcutaneous neoplasms is recommended, covering a broad spectrum of differentiation. In diagnostically challenging cases, select molecular studies can be employed to make critical distinctions between entities sharing morphologic and immunohistochemical properties. Due to sometimes marked differences in prognosis and treatment, knowledge and familiarity with epithelioid soft tissue tumors is key for any surgical pathologist who evaluates skin and subcutaneous biopsies and excision specimens. This concise review provides brief descriptions, key diagnostic features, and important modern ancillary studies for the diagnosis of non-epithelial, non-melanocytic cutaneous tumors that can exhibit a prominent degree of epithelioid morphology.

Plexiform Xanthomatous Tumor, Variety of Xanthoma or Subtype of Fibrohistiocytic Tumors?

Plexiform xanthomatous tumor was proposed as an independent neoplasm within fibrohistiocytic tumor group a few years ago. The arguments were based on their different clinical features as well as their own morphological and immunohistochemical findings. Nevertheless, it has not been widely studied yet, and there are few reports about this entity. Regarding a case, we reviewed the diagnostic characteristics of this underdiagnosed tumor.

[Myxoid variant of angiomatoid fibrous histiocytoma: a clinicopathologic analysis of 3 cases].

Objective: To study clinicopathologic features, diagnosis and differential diagnosis of myxoid variant of angiomatoid fibrous histiocytoma (AFH). Methods: Three cases of myxoid variant of AFHs were collected from First Affiliated Hospital of Nanjing Medical University during 2008 and 2017. EnVision method and fluorescence in situ hybridization(FISH) were used to detect immunophenotype and EWSR1 gene rearrangement, respectively. Results: There were 2 males and l female with age at 13, 31, and 42 years, respectively. The patients presented with a painless mass located superficially (subcutaneous or submucosal) in two cases or deep-seated (retroperitoneum) in one case. Grossly, the diameters of tumors were 1, 7, and 2 cm, respectively. The cut surface was solid and firm, tan to gray in colour. Histologically, the circumscribed tumor had fibrous pseudocapsule and peritumoal lymphoplasmacytic infiltrates. The tumor cells arranged in vaguely nodular growth pattern, with prominent myxoid stroma (present in 60% to 100% of the entire tumor). In hypocellular myxoid areas, the spindle to stellate tumor cells arranged in cords or reticular pattern, or in a haphazard manner. However, histiocytoid cells arranged in fascicular, sheet-like, or whorled growth pattern, as in classical AFH, were also identified in hypercelluar areas. Mild to moderate atypia was observed with low mitotic rate of (0-2)/10 HPF. Tumor necrosis was not seen. One case presented with slit-like hemorrhage and sclerosing collagen intermingled with myxoid matrix was identified in 1 case. Immunohistochemically, all cases were positive for CD68 and CD163. Two of three were positive for desmin, EMA, CD99 and one for Calponin, SMA. All cases were negative for S-100 protein, CD34, CD31, CD35, CD21 and CKpan. FISH detection was positive for EWSRl gene in all cases. Available clinical follow-up was obtained in 2 cases, revealing no evidence of disease in 6 and 89 months, respectively. Conclusions: Myxoid variant of AFH is a histological subtype of AFH, with clinical features, immunophenotypes, genomic profiles and biological behavior similar to typical AFH. Their unusual morphology is easily confused with a variety of other myxoid mesenchymal neoplasms, including myoepithelioma and nerve sheath tumors.

[Pleomorphic and dedifferentiated leiomyosarcoma: a clinicopathologic analysis].

Objective: To investigate the clinicopathologic features, differential diagnosis and biological behavior of pleomorphic leiomyosarcoma (PLMS) and dedifferentiated leiomyosarcoma (DLMS). Methods: Forty-nine cases were collected from November 2007 to December 2016, including eight that diagnosed at Fudan University Shanghai Cancer Center, and 41 consultation cases. The clinical findings and pathologic features were reviewed. Immunophenotype was obtained in 33 cases and follow-up information was available in 38 cases. Results: There were 22 males and 27 females with ages ranging from 24 to 83 years (mean 52.5 years). Fifteen cases occurred in extremities, 14 in deep body cavity, 11 in the trunk, 4 in the head and neck, 2 in the bladder, and 1 each in the inguinal region, perineum and femoral vein, respectively. Tumor sizes ranged from 3 to 30 cm (mean 9.1 cm). The tumors were composed of at least small foci of typical leiomyosarcoma (LMS) and areas of high-grade pleomorphic/undifferentiated sarcoma. The typical LMS component showed the characteristic morphology of smooth muscle differentiation and was low to intermediate grade in most cases. Pleomorphic areas were mainly composed of atypical spindle and polygonal cells admixed with variable large, bizarre atypical cells and multinuclear giant cells, mostly mimicking undifferentiated pleomorphic sarcoma. The pleomorphic and leiomyosarcomatous areas were usually intermixed, but the demarcation may be distinct or gradual in some cases. The classical LMS component was positive for at least one myogenic marker: α-SMA in 97.0%(32/33), desmin in 72.7%(24/33), H-caldesmon in 90.9% (20/22), MSA in 14/16, and calponin in 15/15 of cases. The pleomorphic sarcoma component was reactive for at least one myogenic marker in 87.9% (29/33) of cases, usually showing focal and less intense immunoreactivity than classical LMS component: α-SMA was positive in 81.8%(27/33), desmin in 48.5%(16/33), H-caldesmon in 72.7% (16/22), MSA in 12/16, and calponin in 11/15 of cases. Based on staining for muscle markers in the pleomorphic component, 29 cases were designated as PLMS, 4 as DLMS. Ki-67 index ranged from 15% to 70% (mean 40%). Follow-up data was available in 38 cases (77.6%), of which 11 patients (28.9%) died of disease, 12 patients were alive with unresectable or recurrent disease, 14 patients were alive with no evidence of disease and another one died of unrelated cause. The median disease-free and overall survival was 6 and 10 months respectively. Twelve patients exhibited local recurrence and 11 developed metastases. The median interval to progression was 8 months. Conclusions: The identification of areas of typical LMS is crucial for accurate diagnosis of PLMS and DLMS. Both PLMS and DLMS show more aggressive behavior and poorer prognosis than ordinary LMS.

Primary angiomatoid fibrous histiocytoma of the lung with mediastinal lymph node metastasis.

Angiomatoid fibrous histiocytoma (AFH), a rare soft tissue tumor of borderline malignancy, typically occurs in the subcutis of the accessible soft tissues, most often in children and young adults. Lymph node and/or distant metastasis is seen in less than 2% of patients with AFH. Exceptionally rare examples of AFH have been reported in visceral locations, including the lung. We report a genetically confirmed primary pulmonary AFH in a 70-year-old woman with mediastinal lymph node metastasis, representing to the best of our knowledge the first report of metastases from a visceral AFH.

Transducer-like Enhancer of Split 1 as a Novel Immuno- histochemical Marker for Diagnosis of Synovial Sarcoma.

BACKGROUND: Synovial sarcoma is a mesenchymal neoplasm that accounts for around 10% of all soft tissue sarcomas. The diagnosis of synovial sarcoma can be a challenging task, particularly with small biopsy specimens. AIM: We investigated transducer-like enhancer of split 1 (TLE1), monoclonal antibody, expression by immunohistochemical analysis in a group of 74 synovial sarcoma cases, 20 cases of MPNST, 12 cases of neurofibroma, 15 cases of schwannoma, 5 cases of MFH, 10 cases of lieomyosarcoma and 10 cases of solitary fibrous tumor. MATERIALS AND METHODS: Whole tissue sections were examined: (39 biphasic and 35 monophasic). Nuclear immunoreactivity was scored as negative (<5% of cells positive), 1+(mild /5-25%), 2+ (moderate/25-50%), and 3+ (strong >50%). RESULTS: Overall, 71 (96%) of 74 synovial sarcomas were positive for TLE1, including 37 biphasic (95%) and 34 monophasic (97%) tumors. Other spindle cell tumors showed very low or absent staining of TLE1. CONCLUSIONS: We conclude that TLE1 is a sensitive marker and can be a useful diagnostic marker for synovial sarcoma, particularly the monophasic forms.

[Angiomatoid fibrous histiocytoma in children: 6 cases]. / Histiocytome fibreux angiomatoïde de l'enfant : 6 cas.

BACKGROUND: Angiomatoid fibrous histiocytoma (AFH) is a soft-tissue tumour of uncertain differentiation most often arising in the extremities of children and young adults. AFH is a little-known neoplasm and its rarity may result in it being misdiagnosed as either a reactive lesion or a benign or higher-grade tumour. We report 6 cases of AFH in children and we review the clinicopathological and molecular features of this neoplasm published in the literature. PATIENTS AND METHODS: The children (aged 4 to 16 years) presented a single nodule involving the forearm (4/6), the trunk or the buttock, and all 5 nodules appeared spontaneously. Microscopic examination revealed well-circumscribed nodular lesions comprising a fibrous pseudo-capsule, haemorrhagic non-endothelial-lined pseudocystic spaces, and sheets of spindle and ovoid cells with dense surrounding lymphoplasmacytic infiltrate. Tumours were positive for desmin, CD68, CD99 and smooth-muscle actin markers. A fusion gene (EWSR1-ATF1) was found in the 3 cases in which molecular investigation was performed. DISCUSSION: In our series, a diagnosis of AFH had in no event been evoked after clinical examination and radiological investigation. The diagnosis was based in all cases on recognition of characteristic features during histological examination and it was confirmed in 3 cases by the recognition of fusion genes. Complete excision with wide margins allowed complete cure in all cases, supporting a good prognosis of AFH, although long-term follow-up is still mandatory to rule out relapse or metastases, which although rare, are responsible for fatal cases. To avoid unnecessary surgery in patients with AFH, an ultrasound core-needle biopsy should be performed as a first step in order to provide precise diagnosis enabling complete excision to be performed, with the margins being decided in multidisciplinary meetings involving teams specialised in soft-tissue tumours.

Spindle Cell Atypical Fibroxanthoma: Myofibroblastic Differentiation Represents a Diagnostic Pitfall in This Variant of AFX.

Atypical fibroxanthoma (AFX) is a low-grade, dermal, mesenchymal neoplasm, which lacks a specific lineage of differentiation. The classical histologic appearance of AFX is that of a pleomorphic and spindle cell neoplasm with marked nuclear pleomorphism, mitotic figures, and often prominent storiform pattern that superficially resembles a pleomorphic high-grade sarcoma ("malignant fibrous histiocytoma"). Many histologic variants have been described. We have reviewed 15 cases of AFX characterized by a pure spindle cell morphology that could be easily mistaken for other spindle cell dermal neoplasms. All of our cases were stained with CD68, CD163, CD10, S-100p, p63, wide-spectrum keratin, CD31, CD34, smooth muscle actin (SMA), desmin, calponin, and h-caldesmon. All 15 cases showed an immunoprofile consistent with AFX. In 9 cases, SMA was also strongly expressed; this finding, coupled with the malignant spindle cell histomorphology, can lead to an erroneous diagnosis of cutaneous leiomyosarcoma with potential clinical consequences. Awareness of this pattern of immunoreactivity in this unusual variant of AFX is of importance for avoiding diagnostic misinterpretation. This study intends to characterize the nature and frequency of SMA immunoreactivity in AFX and to discuss the potential diagnostic pitfalls of immunohistochemical markers in distinguishing this entity from other malignant spindle cell neoplasms.

The vascular marker CD31 also highlights histiocytes and histiocyte-like cells within cutaneous tumors.

OBJECTIVES: While useful in diagnosing angiosarcomas, CD31 can also highlight histiocytes within soft tissue tumors and lead to errors in diagnosis. We sought to determine how often CD31 highlights cutaneous histiocytomas and histiocytoma mimics. METHODS: We examined eight epithelioid cell histiocytomas (ECHs), 12 xanthogranulomas (XGs), nine cases of Langerhans cell histiocytosis (LCH), eight reticulohistiocytomas, 11 xanthomas, 29 atypical fibroxanthomas, nine granular cell tumors, four cases of angiolymphoid hyperplasia with eosinophilia, nine intradermal Spitz nevi, and nine angiosarcomas with antibodies directed against CD31, CD34, CD163, and factor VIII. RESULTS: CD31 marked cells in three of 12 XGs, four of nine cases of LCH, one of eight reticulohistiocytomas, one of 11 xanthomas, 10 of 29 atypical fibroxanthomas, four of four cases of angiolymphoid hyperplasia with eosinophilia, nine of nine angiosarcomas, zero of nine granular cell tumors, and zero of eight ECHs. CD34 and factor VIII were negative in all nonvascular cases. CONCLUSIONS: Our results indicate that CD31 can mark lesional cells and imitate vascular tumors in cutaneous histiocytomas and histiocytoma mimics, an error that can be avoided by using a panel of antibodies.

Angiomatoid Fibrous Histiocytoma With Prominent Myxoid Stroma: A Case Report and Review of the Literature.

Angiomatoid fibrous histiocytoma is a rare neoplasm of intermediate malignant potential that usually occurs in the dermis or subcutaneous tissues of the extremities in children or young adults. It is characterized by a nodular growth of spindled, histiocytic, or epithelioid cells and blood-filled spaces, surrounded by a fibrous pseudocapsule that contains a lymphocytic cuff. The histological spectrum of this condition has expanded to include cases that contain prominent myxoid stroma. We herein present another instance of myxoid angiomatoid fibrous histiocytoma and review the clinical and histological features, immunohistochemical profile, and molecular genetics of this uncommon variant. We also discuss the diagnostic mimics of this condition, including benign myxoid soft tissue tumors and sarcomas, to illustrate the potential pitfalls in arriving at the diagnosis.

Myxoid variant of so-called angiomatoid "malignant fibrous histiocytoma": clinicopathologic characterization in a series of 21 cases.

Angiomatoid "malignant fibrous histiocytoma" (AMFH) is a tumor of intermediate malignancy and undefined lineage, mostly arising in the extremities of young patients. Examples with a prominent myxoid matrix are very uncommon. Twenty-one cases of myxoid AMFH (among a total of 414) identified in consult files are described, including clinicopathologic features, fluorescence in situ hybridization analysis in a subset of cases, and follow-up. Thirteen patients were female and 8 male, ranging in age from 2 to 51 y (median 17 y). These circumscribed tumors arose in subcutaneous or deep somatic soft tissue, with a median size of 2.5 cm (range, 1 to 8 cm), being located in the extremities (14/21), trunk (4/21), and upper limb girdle (3/21). Characteristic features included a fibrous pseudocapsule (20/21), peritumoral lymphoplasmacytic infiltrates (20/21), blood-filled cystic spaces (17/21), and prominent myxoid morphology comprising 60% to 100% of the tumor surface area examined. Histiocytoid or spindled tumor cells exhibited vesicular nuclei, inconspicuous nucleoli, palely eosinophilic cytoplasm, and multinodular growth without necrosis. Mucin pools and scattered multinucleate giant cells were observed in a subset of cases. Mild to moderate atypia was observed in 4 cases; 1 tumor showed a pseudochondroid matrix. Immunohistochemically, 14/21 cases expressed desmin, 12/21 expressed EMA, and 4/7 exhibited EWSR1 rearrangement. Follow-up, available for 11 patients (median, 43 mo), revealed that 3 developed local recurrence after 2, 7, and 48 months, respectively. All patients were alive without metastases. AMFH may present with prominent myxoid features making diagnosis difficult and causing possible confusion with other myxoid tumors including low-grade fibromyxoid sarcoma, extraskeletal myxoid chondrosarcoma, and myxoid liposarcoma.

Angiomatoid fibrous histiocytoma: clinicopathological and molecular characterisation with emphasis on variant histomorphology.

AIMS: Angiomatoid fibrous histiocytoma (AFH) is histologically typified by nodules of histiocytoid spindle cells with pseudoangiomatoid spaces, fibrous pseudocapsules and lymphocytic cuffs. The principal goal was to expand the spectrum of AFHs through clinicopathological and molecular characterisation. METHODS: Thirteen AFHs, including 11 with confirmed hallmark translocation, were reappraised for classic features, reactive osteoclasts, mitoses and stromal, architectural and cytomorphological variations, with CD99, desmin and EMA stained in available cases. RESULTS: Seven male and six female patients ranged in age from 4 to 63 years (median, 13), including 4 older than 20 years. Tumours were located on the extremities (n=6), trunk (n=4) and scalp (n=3). Although fibrous pseudocapsules were observed in all cases, four showed solid histology without pseudoangiomatoid spaces and another one lacked peripheral lymphoid infiltrates. Nuclear pleomorphism was striking in two cases, moderate in seven and absent in four, with osteoclasts seen in two cases. In three AFHs with sclerotic matrix, one exhibited perivascular hyalinisation and nuclear palisading, reminiscent of a schwannoma. In three varyingly myxoid tumours, one closely resembled a myoepithelioma with prominent reticular arrangement of spindle cells in an abundant myxoid stroma. Besides EWSR1 gene rearrangement detected in four cases by fluorescence in situ hybridisation (FISH), EWSR1-CREB1 fusion was confirmed in nine cases, including a schwannoma-like AFH, and EWSR1-ATF1 fusion detected in a myoepithelioma-like AFH. Immunohistochemically, 56% of AFHs were positive for EMA, 78% for desmin and 100% for CD99. CONCLUSIONS: Molecular testing is diagnostic of variant AFHs displaying diverse histomorphological alterations in the architectural patterns, cytomorphology and extracellular matrix.

Diagnostic and therapeutic strategy and the most efficient prognostic factors of breast malignant fibrous histiocytoma.

We analyzed the clinicopathological features of 9 breast malignant fibrous histiocytoma (MFH) patients. Immunohistochemistry was used to make both diagnosis and differential diagnosis, and to identify prognostic factors. All tumors lacked epithelial markers but expressed mesenchymal markers, suggesting a mesenchymal origin. Of the five cases expressing Ki-67, two of three patients with axillary lymph node involvement died between 6-8 months, and two died at 17 and 26 months after diagnosis. The two remaining cases, with low Ki-67 expression, had no recurrent or metastatic disease at 145 months after diagnosis. Previous studies have shown that surgery is the primary treatment of choice, but no clear benefit from adjuvant chemotherapy was observed. We demonstrate that axillary lymph node involvement and high expression of Ki-67 are associated with poorer prognosis. A literature review indicates surgery remains the first choice for MFH, but benefits from adjuvant chemotherapy remain unclear.

Primary inflammatory malignant fibrous histiocytoma of the breast: a case report of an unusual variant and review of the literature.

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adults, but its presence in the breast is rare. We report a case of primary inflammatory MFH in a 72-year-old Caucasian female with no previous medical history and no prior radiation exposure. She presented with a palpable mass that was suspicious for malignancy on mammography. Histologic evaluation of the core needle biopsy revealed sheets of large, pleomorphic neoplastic cells within a dense background of acute and chronic inflammatory cells. The neoplastic cells exhibited a moderate to abundant amount of finely vacuolated cytoplasm and atypical nuclei with vesicular nuclear chromatin and prominent nucleoli. Mitotic activity was readily identified, and foci of necrosis were noted. The neoplastic cells were immunoreactive with CD68, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and vimentin. The diagnosis of MFH was rendered after thorough microscopic examination of the entire mass following mastectomy. MFH of the breast is a diagnosis of exclusion. The definitive treatment of MFH is surgical, either with wide local excision or total mastectomy. The roles of sentinel lymph node biopsy, axillary lymph node dissection, chemotherapy, and radiation have yet to be definitively clarified. The prognosis of MFH of the breast is generally poor.

A major response to trabectedin in metastatic malignant fibrous histiocytoma of the vertebra: a case report and review of the literature.

Malignant fibrous histiocytoma is an aggressive tumor, the most common soft-tissue sarcoma of adult age. It is usually located in the extremities and retroperitoneum, and very rarely there is skeletal involvement. Surgery is the preferred treatment in early disease; in advanced disease, chemotherapy is the main therapeutic strategy. We present a 25-year-old female patient diagnosed with a vertebral mass in T5 with a severely compromised spinal cord. She underwent surgical decompression and the pathological findings were consistent with malignant fibrous histiocytoma. After several surgical treatments she had pulmonary progression and was therefore started on chemotherapy. She had a very poor response to most of the administered regimens until she initiated trabectedin 1 mg/m 2 every three weeks. She showed a significant improvement with a major response of the lung metastases. This report indicates that trabectedin is an active drug in advanced, previously treated metastatic malignant fibrous histiocytoma.

Atypical fibroxanthoma developing on a pacemaker pocket mimicking a pyogenic granuloma.

Malignant tumors at the site of implantation of a pacemaker generator, although rare, have been reported in the literature. We present a case of an 89-year-old man with atypical fibroxanthoma in a pacemaker pocket. The device had been implanted for more than 4 years. An exophytic tumor had developed in this place and was clinically interpreted as a pyogenic granuloma. An excisional biopsy revealed the nature of the tumor. To our knowledge, the association of atypical fibroxanthoma arising from a pacemaker pocket has not been previously reported. A review of the literature has revealed four malignant soft tissue tumors previously reported at the pacemaker site. Routine examination in all patients with implanted pacemaker generators should be practiced at follow-up visits. This would allow an early diagnosis of a malignant associated neoplasm. Pathologists should become familiar with this type of devices and their potential neoplastic complications.