David Creytens

Leukocyte infiltration and tumor cell plasticity are parameters of aggressiveness in primary cutaneous melanoma

Various clinical and experimental observations detected an immunological host defense in cutaneous melanoma. In order to investigate the prognostic value of leukocyte effector mechanisms, we examined the presence of different subsets of leukocytes in tumor samples of 58 patients diagnosed with primary cutaneous melanoma. The presence of T lymphocytes, cytotoxic T lymphocytes, B lymphocytes, CD16+ cells and macrophages was correlated to Breslow depth. A significantly higher amount of several subsets of leukocytes was found in samples with a more progressed tumor stage and survival analysis demonstrated that a higher amount of T lymphocytes and CD16+ cells was associated with a short survival. The amount of FOXP3+ regulatory T lymphocytes did not correlate with survival, nevertheless, it correlated with the amount of total infiltrate. In contrast, analysis of the expression of CD69, a marker for activated lymphocytes, demonstrated that patients with a higher amount of CD69+ lymphocytes had a better survival. In addition, a new parameter for aggressiveness of melanoma, tumor cell plasticity [i.e., the presence of periodic acid Schiff’s (PAS) reagent positive loops], also predicted short survival and a trend of a higher amount of tumor infiltrating leukocytes in tumors with PAS positive loops was observed. These findings demonstrate that leukocyte infiltration and the presence of PAS loops is a sign of tumor aggressiveness and may have prognostic value.

EWSR1-ATF1 chimeric transcript in a myoepithelial tumor of soft tissue: a case report

Soft tissue myoepithelial tumors, a recently defined entity, include benign and malignant lesions showing a considerable morphological and immunohistochemical heterogeneity. EWSR1 rearrangements are well recognized in this tumor type, and some of the partner genes have been identified. Herein we describe a soft tissue myoepithelioma arising in the pelvis with an EWSR1-ATF1 fusion, therefore extending the spectrum of partner genes of EWSR1. In addition, this case indicates that there are overlapping genetic features of myoepithelial tumors, clear cell sarcoma, angiomatoid fibrous histiocytoma, and hyalinizing clear-cell carcinoma of the salivary gland.

Atypical spindle cell lipoma: a clinicopathologic, immunohistochemical, and molecular study emphasizing its relationship to classical spindle cell lipoma.

We studied a series of spindle cell lipomas arising in atypical sites and showing unusual morphologic features (which we called atypical spindle cell lipoma) to assess if these lesions have the same chromosomal alterations as classical spindle cell lipoma but different from those found in atypical lipomatous tumor/well-differentiated liposarcoma. We investigated alterations of different genes in the 13q14 region and the amplification status of the MDM2 and CDK4 genes at 12q14-15 by multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) analysis. In the atypical spindle cell lipomas, MLPA revealed deletions in the two nearest flanking genes of RB1 (ITM2B and RCBTB2) and in multiple important exons of RB1. In contrast, in classical spindle cell lipomas, a less complex loss of RB1 exons was found but no deletion of ITM2B and RCBTB2. Moreover, MLPA identified a deletion of the DLEU1 gene, a finding which has not been reported earlier. We propose an immunohistochemical panel for lipomatous tumors which comprises of MDM2, CDK4, p16, Rb, which we have found useful in discriminating between atypical or classical spindle cell lipomas and other adipocytic neoplasms, especially atypical lipomatous tumor/well-differentiated liposarcoma. Our findings strengthen the link between atypical spindle cell lipoma and classical spindle cell lipoma, and differentiate them from atypical lipomatous tumor/well-differentiated liposarcoma.

Presence of C11orf95-MKL2 fusion is a consistent finding in chondroid lipomas: a study of eight cases

Chondroid lipomas are benign adipose tissue tumours. Their rarity and peculiar morphology can lead to misinterpretation, especially in small biopsies. Based on a recurrent translocation t(11;16)(q13;p13), the C11orf95–MKL2 fusion gene has been found in a few cases. Therefore, it seemed appropriate to look for this fusion gene in a larger cohort.

Retroperitoneal Liposarcoma: Current Insights in Diagnosis and Treatment

Retroperitoneal liposarcoma (RLS) is a rare, biologically heterogeneous tumor that present considerable challenges due to its size and deep location. As a consequence, the majority of patients with high-grade RLS will develop locally recurrent disease following surgery, and this constitutes the cause of death in most patients. Here, we review current insights and controversies regarding histology, molecular biology, extent of surgery, (neo)adjuvant treatment, and systemic treatment including novel targeted agents in RLS.

Nuclear expression of STAT6 in dedifferentiated liposarcomas with a solitary fibrous tumor-like morphology: a diagnostic pitfall

To the Editor: Nuclear STAT6 (Signal Transducer and Activator of Transcription 6) immunoreactivity has been reported as an excellent surrogate marker for the NAB2-STAT6 gene fusion, which is the defining driver mutation of solitary fibrous tumor (SFT).1–3 Doyle et al4 described the utility of STAT6 expression as a tool to distinguish SFT from a large group of benign and malignant histologic mimics, including dedifferentiated liposarcoma (DDLPS). Very recently, Doyle et al reported STAT6 amplification and nuclear STAT6 expression in a small subset of DDLPS, all with a predominant spindle cell and/ or pleomorphic cytomorphology, which is the most common histologic appearance of DDLPS. We performed a study on 40 cases of DDLPS of which the diagnosis was previously confirmed by MDM2 immunohistochemistry (1:10; IF2; Invitrogen, Carlsbad, CA) and fluorescence in situ hybridization analysis for MDM2 amplification using the LSI MDM2 (12q15) DNA probe with CEP12 (Abbott Laboratories, Abbott Park, IL). Dedifferentiated areas in DDLPS exhibit a wide morphologic spectrum and can show a peculiar predominant SFT-like (hemangiopericytoma-like) growth pattern, which could be a diagnostic pitfall. The morphology of the selected DDLPS in our study resembled high-grade pleomorphic sarcoma, high-grade spindle cell

'Atypical' pleomorphic lipomatous tumor : a clinicopathologic, immunohistochemical and molecular study of 21 cases, emphasizing its relationship to atypical spindle cell lipomatous tumor and suggesting a morphologic spectrum (atypical spindle cell/pleomorphic lipomatous tumor)

The classification of the until recently poorly explored group of atypical adipocytic neoplasms with spindle cell features, for which recently the term atypical spindle cell lipomatous tumor (ASLT) has been proposed, remains challenging. Recent studies have proposed ASLT as a unique entity with (in at least a significant subset of cases) a specific genetic background, namely deletions/losses of 13q14, including RB1 and its flanking genes RCBTB2, DLEU1, and ITM2B. Similar genetic aberrations have been reported in pleomorphic liposarcomas (PLSs). This prompted us to investigate a series of 21 low-grade adipocytic neoplasms with a pleomorphic lipoma–like appearance, but with atypical morphologic features (including atypical spindle cells, pleomorphic [multinucleated] cells, pleomorphic lipoblasts and poor circumscription), for which we propose the term “atypical” pleomorphic lipomatous tumor (APLT). Five cases of PLS were also included in this study. We used multiplex ligation-dependent probe amplification to evaluate genetic changes of 13q14. In addition, array-based comparative genomic hybridization was performed on 4 APLTs and all PLSs. Multiplex ligation-dependent probe amplification showed consistent loss of RB1 and its flanking gene RCBTB2 in all cases of APLT. This genetic alteration was also present in all PLSs, suggesting genetic overlap, in addition to morphologic overlap, with APLTs. However, array-based comparative genomic hybridization demonstrated more complex genetic alterations with more losses and gains in PLSs compared with APLTs. APLTs arose in the subcutis (67%) more frequently than in the deep (subfascial) soft tissues (33%). With a median follow-up of 42 months, recurrences were documented in 2 of 12 APLTs for which a long follow-up was available. Herein, we also demonstrate that APLTs share obvious overlapping morphologic, immunohistochemical, genetic and clinical characteristics with the recently defined ASLT, suggesting that they are related lesions that form a spectrum (atypical spindle cell/pleomorphic lipomatous tumor).

Detection of MDM2/CDK4 Amplification in Lipomatous Soft Tissue Tumors From Formalin-fixed, Paraffin-embedded Tissue: Comparison of Multiplex Ligation-dependent Probe Amplification (MLPA) and Fluorescence In Situ Hybridization (FISH)

In this study, the detection of MDM2 and CDK4 amplification was evaluated in lipomatous soft tissue tumors using multiplex ligation-dependent probe amplification (MLPA), a PCR-based technique, in comparison with fluorescence in situ hybridization (FISH). These 2 techniques were evaluated in a series of 77 formalin-fixed, paraffin-embedded lipomatous tumors (27 benign adipose tumors, 28 atypical lipomatous tumors/well-differentiated liposarcomas, 18 dedifferentiated liposarcomas, and 4 pleomorphic liposarcomas). Using MLPA, with a cut-off ratio of >2, 36/71 samples (22 atypical lipomatous tumors/well-differentiated liposarcomas, and 14 dedifferentiated liposarcomas) showed MDM2 and CDK4 amplification. Using FISH as gold standard, MLPA showed a sensitivity of 90% (36/40) and a specificity of 100% (31/31) in detecting amplification of MDM2 and CDK4 in lipomatous soft tissue tumors. In case of high-level amplification (MDM2-CDK4/CEP12 ratio >5), concordance was 100%. Four cases of atypical lipomatous tumor/well-differentiated liposarcoma (4/26, 15%) with a low MDM2 and CDK4 amplification level (MDM2-CDK4/CEP12 ratio ranging between 2 and 2.5) detected by FISH showed no amplification by MLPA, although gain of MDM2 and CDK4 (ratios ranging between 1.6 and 1.9) was seen with MLPA. No amplification was detected in benign lipomatous tumors and pleomorphic liposarcomas. Furthermore, there was a very high concordance between the ratios obtained by FISH and MLPA. In conclusion, MLPA proves to be an appropriate and straightforward technique for screening MDM2/CDK4 amplification in lipomatous tumors, especially when a correct cut-off value and reference samples are chosen, and could be considered a good alternative to FISH to determine MDM2 and CDK4 amplification in liposarcomas. Moreover, because MLPA, as a multiplex technique, allows simultaneous detection of multiple chromosomal changes of interest, it could be in the future a very reliable and fast molecular analysis on paraffin-embedded material to test for other diagnostically, prognostically, or therapeutically relevant genomic mutations in lipomatous tumors.

Array-based comparative genomic hybridisation analysis of a pleomorphic myxoid liposarcoma

Pleomorphic myxoid liposarcoma, first described and defined by Alaggio et al 1 ,2 as a neoplasm showing mixed distinctive histological features of conventional myxoid liposarcoma and pleomorphic liposarcoma and usually occurring in young patients, is a very rare and still poorly explored and under-recognised tumour entity. Boland et al 3 reported an additional series of these lesions in the mediastinum of young patients with morphological features of a pleomorphic liposarcoma with prominent myxoid changes composed of areas resembling myxoid liposarcoma juxtaposed to myxoid areas containing bizarre pleomorphic lipoblasts. At present, it is still unclear whether this sarcoma represents a high-grade variant of a myxoid liposarcoma, a distinct morphologic myxoid variant of a conventional pleomorphic liposarcoma or an unique form of liposarcoma. We report the case of a 21-year-old male who presented with a large mass with a maximal diameter of 16 cm arising in the neck. Histology of the resection revealed a myxoid, infiltrative growing tumour consisting of a homogeneous myxoid matrix containing ‘lymphangioma-like’ myxoid pools, a delicate plexiform capillary network and scattered lipoblasts (figure 1 …

Diagnostic Utility of STAT6 Immunohistochemistry in the Diagnosis of Fat-forming Solitary Fibrous Tumors.

To the Editor: Fat-forming solitary fibrous tumor (SFT) (also known as lipomatous hemangiopericytoma) is a rare, usually slowly growing, fibroblastic neoplasm, characterized by the histologic features of typical or cellular SFT with, in addition, a variably prominent mature adipocytic component.1–3 The fat-forming variant of SFT occurs predominantly in the retroperitoneum and in the deep soft tissues of the lower extremities and the trunk. Although fat-forming SFTs are generally regarded as nonrecurring and nonmetastasizing benign tumors, they can show malignant behavior and a few fatforming SFTs with malignant histologic features have been reported. Histologically, malignant fat-forming SFTs exhibit at least focal hypercellularity, showing increased mitotic index (>4 mitoses per 10HPF), variable cytologic atypia, and/or necrosis. Nuclear signal transducer and activator of transcription 6 (STAT6) immunoreactivity has been reported as an excellent surrogate marker for theNAB2-STAT6 gene fusion, which is the defining driver mutation of benign and malignant SFTs. Recent studies described the utility of STAT6 expression as a tool to distinguish SFT from a large group of benign and malignant histologic mimics. In these studies nuclear expression of STAT6 was pres-