Synovial Sarcoma of the Kidney: Diagnostic Pitfalls in a Case with Myxoid Monophasic Differentiation and No Epithelial Biomarkers Expression.

Synovial sarcomas are soft tissue tumours of uncertain origin, most commonly found in the upper or lower extremities. They are characterised by distinctive chromosomal rearrangements involving the gene SS18. Synovial sarcomas can occasionally arise also in visceral sites, but retroperitoneal SSs are very unusual. Among them, a few primary renal synovial sarcomas have been described in the scientific literature. Primary renal synovial sarcomas tend to be monophasic and often show cystic changes. Histologically, they can closely resemble other primary kidney tumours, mainly paediatric tumours such as nephroblastoma and clear cell sarcoma of the kidney. In the current work, a primary synovial sarcoma of the kidney with unusual morphological features (extensively myxoid stroma and immunohistochemical positivity for BCOR) is described. Molecular analysis, through targeted RNA sequencing, was of invaluable help in reaching the correct diagnosis. Despite locally advanced disease at presentation, the patient showed an unexpectedly brilliant response to chemotherapy.

Soft tissue tumours of the penis. The 30-year Istituto Nazionale Tumori di Milano experience.

Objective: Small series and individual cases of penile soft tissue tumours are reported in the literature: these are rare tumours that represent less than 5% of all penile tumours. Methods: Penile soft tissue tumours were collected from the archive of the Department of Pathology at the Istituto Nazionale dei Tumori of Milan between January 1990 and October 2021. All available medical records were retrieved and reviewed to obtain clinical information. Results: Our series refers to the 30-year experience of highlighting the heterogeneity in the presentation and microscopic features of these rare sarcomas. 18 penile soft tissue tumours are described, 4 benign and 14 malignant. The mean age at diagnosis was 58.2 years (range 24-96 years) and 53.6 years among malignancies (range 24-89). The most frequent histotype was Kaposi's sarcoma (nr = 4) and very unusual histotypes were observed, namely low-grade fibromyxoid sarcoma, synovial sarcoma, proximal type epithelioid sarcoma and the first reported case of dedifferentiated liposarcoma of the penis. Conclusions: Among sarcomas of the genitourinary tract, tumours of the soft tissues of the penis are the rarest. Penile sarcomas can present at a young age. Kaposi's sarcoma in HIV-negative patients has a favorable outcome, while deep sarcomas have an aggressive behavior and poor prognosis.

Diagnostic utility of FOXO1 immunohistochemistry for rhabdomyosarcoma classification.

AIMS: Rhabdomyosarcomas currently are classified into one of four subtypes (alveolar, embryonal, spindle cell/sclerosing, or pleomorphic) according to their morphological, immunohistochemical, and molecular genetic features. The alveolar subtype is characterised by a recurrent translocation involving PAX3 or PAX7 and FOXO1; identification of this translocation is important for appropriate classification and prognostication. In this study, we aimed to explore the diagnostic utility of FOXO1 immunohistochemistry for rhabdomyosarcoma classification. METHODS/RESULTS: A monoclonal antibody targeting a FOXO1 epitope retained in the fusion oncoprotein was used to study 105 rhabdomyosarcomas. FOXO1 was positive for expression by immunohistochemistry in all 25 alveolar rhabdomyosarcomas, with 84% showing diffuse expression in greater than 90% of neoplastic cells; the remainder of alveolar rhabdomyosarcomas displayed at least moderate staining in a minimum of 60% of lesional cells. Apart from three spindle cell rhabdomyosarcomas showing heterogeneous nuclear immunoreactivity in 40-80% of tumour cells, the 80 cases of embryonal, pleomorphic, and spindle cell/sclerosing rhabdomyosarcoma were negative for FOXO1 expression (96.3% specific) when using a threshold of nuclear staining in 20% of neoplastic cells to determine positivity. Variable cytoplasmic staining was present in a fraction of all rhabdomyosarcoma subtypes. Nonneoplastic lymphocytes, endothelial cells, and Schwann cells also showed variably intense nuclear anti-FOXO1 immunoreactivity. CONCLUSION: Taken together, our findings suggest that FOXO1 immunohistochemistry is a highly sensitive and relatively specific surrogate marker of the PAX3/7::FOXO1 fusion oncoprotein in rhabdomyosarcoma. Cytoplasmic immunoreactivity, expression in nonneoplastic tissues, and limited nuclear staining of nonalveolar rhabdomyosarcomas represent potential pitfalls in interpretation.

Benign mesenchymal tumours of the tongue: A report of adult-type rhabdomyoma and granular cell tumour with a review of the literature.

The cytomorphological features of benign mesenchymal tumours of the tongue have rarely been reported. Herein, we present the cytomorphological features of adult-type rhabdomyoma, which occurred in the tongue of a female patient, and granular cell tumour (GCT), which occurred in the tongue of a male patient; both patients were in their mid-50s. The cytological features of the adult-type rhabdomyoma case included large polygonal to ovoid cells with abundant and granular cytoplasm with predominantly peripherally located, uniform, round to oval nuclei and small nucleoli. Cross-striation and crystalline intracytoplasmic structures were not seen. The cytological features of the GCT case included large cells with abundant granular pale cytoplasm, small round nuclei and small distinct nucleoli. The cytological differential diagnoses of these tumours overlap; thus, the cytological findings of the different entities included in their differential diagnoses are discussed.

Histologic characterization of paediatric mesenchymal neoplasms treated with kinase-targeted therapy.

AIMS: Recurrent alterations involving receptor tyrosine or cytoplasmic kinase genes have been described in soft-tissue neoplasms such as infantile fibrosarcoma (IFS) and inflammatory myofibroblastic tumour (IMT). Recent trials and regulatory approvals for targeted inhibitors against the kinase domains of these oncoproteins have allowed for increased use of targeted therapies. We aimed to characterize the histologic features of paediatric mesenchymal neoplasms with kinase alterations treated with targeted inhibitors. METHODS AND RESULTS: Eight patients with tyrosine kinase-altered mesenchymal neoplasms with pre- and posttreatment samples were identified. Tumours occurred in five females and three males with a median age at presentation of 6.5 years. Tumour sites were bone/somatic soft-tissue (n = 5) and viscera (n = 3). Pretreatment diagnoses were: IMT (n = 3), epithelioid inflammatory myofibroblastic sarcoma (n = 1), and descriptive diagnoses (n = 4) such as "kinase-driven spindle cell tumor." Fusions identified were ETV6::NTRK3 (n = 2), TPM3::NTRK1, SEPT7::BRAF, TFG::ROS1, KLC1::ALK, RANBP2::ALK, and MAP4::RAF1. Patients were treated with larotrectinib (n = 3), ALK or ALK/ROS1 inhibitors (n = 3), and MEK inhibitors (n = 2). Posttreatment tumours exhibited a striking decrease in cellularity (7/8) and the presence of collagenous stroma (7/8) with extensive glassy hyalinization (5/8). In two cases, abundant coarse or psammomatous calcifications were seen and in one case prominent perivascular hyalinization was noted. Residual viable tumour was seen in 3/8 cases (<5% in one case, and >75% in 2/8 cases). CONCLUSION: Mesenchymal neoplasms with tyrosine kinase alterations treated with targeted inhibitors show a pathologic response, which includes decreased cellularity and stromal hyalinization. The presence of these features may be helpful in assessing tumour response after targeted therapy.

Test Yourself-Question: Multiple facial skin lesions associated with gingival hypertrophy in a pair of siblings.

Two brothers, completely asymptomatic until their first year of life, started to complain from gingival hypertrophy, progressive development of painful soft tissue masses on the fingers and toes, on the face and on the scalp. There were no neurological symptoms or mental delay for both brothers.

MUC4 is expressed in alveolar rhabdomyosarcoma.

AIMS: Mucin 4 (MUC4) is a transmembrane glycoprotein normally expressed by several human epithelial surfaces, including those of the colon, vagina, and respiratory tract. Although MUC4 overexpression is seen in various carcinomas, its expression among mesenchymal neoplasms is fairly specific to low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma. Having observed unanticipated anti-MUC4 immunoreactivity in rhabdomyosarcoma, we aimed to further characterise its expression. METHODS AND RESULTS: Expression of MUC4 was assessed by immunohistochemistry in a total of 97 rhabdomyosarcomas using formalin-fixed paraffin-embedded tissue sections. MUC4 was expressed by 21 of 26 PAX3/7-FOXO1 fusion-positive cases, wherein immunoreactivity, varying from weak to strong, was present in 20-100% of neoplastic cells. With the exception of one sclerosing rhabdomyosarcoma showing immunoreactivity in 20% of cells, MUC4 was not expressed by embryonal (n = 28), sclerosing (n = 20), or pleomorphic (n = 23) rhabdomyosarcomas. Analysing published gene expression microarray data from a separate cohort of 33 fusion-positive and 25 fusion-negative rhabdomyosarcomas, we found on average a 11.4-fold increased expression in fusion-positive tumours (P = 0.0004). CONCLUSIONS: MUC4 is expressed to a variable extent in the majority of PAX3/7-FOXO1 fusion-positive (alveolar) rhabdomyosarcomas, while expression in other rhabdomyosarcoma subtypes is rare.

Recent developments in gastroesophageal mesenchymal tumours.

The pathologist's approach to gastroesophageal mesenchymal tumours has changed dramatically during the last 25 years. In particular, gastrointestinal stromal tumour (GIST) has evolved from a wastebasket mesenchymal tumour category to a precisely defined entity with an increasingly detailed genetic subclassification. This subclassification has brought gastrointestinal mesenchymal neoplasia into the realm of precision medicine, with specific treatments optimised for particular genetic subtypes. Molecular genetic data have also greatly improved our understanding of oesophageal mesenchymal tumours, including the discovery that so-called 'giant fibrovascular polyps' in fact represent a clinically distinctive presentation of well-differentiated liposarcoma. Here, we will focus on gastroesophageal mesenchymal tumours for which there have been recent developments in classification, molecular genetics or tumour biology: granular cell tumour, 'giant fibrovascular polyp'/well-differentiated liposarcoma, plexiform fibromyxoma, gastroblastoma and, of course, GIST.

Revisiting cytomorphology, including unusual features and clinical scenarios of 8 cases of alveolar soft part sarcoma with TFE3 immunohistochemical staining in 7 cases.

OBJECTIVES: To present a comprehensive analysis of cytomorphological features, including clinical scenarios, for 8 cases (4 males, 4 females, aged 17-39 years, average = 28.5) of, retrospectively diagnosed alveolar soft part sarcoma (ASPS), with TFE3 immunostaining in 7 cases. METHODS: Conventional Papanicolaou and May Grunwald-Giemsa (MGG) stained smears and corresponding tissue sections were critically reviewed. Fine needle aspiration cytology was performed for primary diagnosis in 6 cases and for metastatic lesions in 2 cases. TFE3 and other immunohistochemical stains were tested using polymer detection technique. RESULTS: Tumour sites were thigh (n = 6), shoulder (1) and neck (1). Tumour size (n = 6) varied from 5 to 14.5 cm (average = 7.2). Seven out of 8 cases were correctly diagnosed on cytosmears. The smears were mostly hypercellular (5), composed of cohesive clusters (8), including cell balls and pseudopapillae (3) and singly scattered cells (8). Tumour cells were round to oval, containing central to eccentric nuclei (8), abundant granular (8) to finely vacuolated (7) cytoplasm that was ill- to well-defined, intracytoplasmic rod-like or needle-shaped crystals (3) and prominent nucleoli (8), Additionally, there were binucleated cells (7), multinucleation (2), intracytoplasmic inclusions (3), intranuclear inclusions (2), intercellular stroma (5) and bare nuclei (8). Immunohistochemically, 7/8 tumours were positive for TFE3. CONCLUSIONS: This constitutes the largest series describing cytomorphological spectrum of ASPS with TFE3 immunostaining results. Frequently observed features and rod-like/needle-shaped crystals on MGG smears, can help to differentiate ASPS from its mimics. TFE3 immunostaining aids in substantiating diagnoses, in an appropriate clinicoradiological context.

The importance of diffusion apparent diffusion coefficient values in the evaluation of soft tissue sarcomas after treatment.

PURPOSE: In our study, we aimed to show the efficiency of diffusion-weighted images at different b-values and apparent diffusion coefficient (ADC) values in the differentiation of recurrent tumours from post-treatment tissue changes. MATERIAL AND METHODS: The conventional and diffusion magnetic resonance images (MRIs) of 42 patients operated for soft tissue sarcomas between June 2012 and March 2015 followed up with MRIs that were evaluated by 2 radiologists retrospectively. Diffusion MRIs were acquired at 4 different b-values (50, 400, 800, 1000 s/mm2). The lesions were classified according to conventional MRI findings as post-treatment changes and recurrent tumours. RESULTS: When the patient group with recurrent tumours was compared with the patient group with postoperative changes the ADC calculations were statistically significantly lower for the recurrent tumours at all b-levels (p < 0.001 for all b-levels). The sensitivity of b-50 values lower than 3.01 × 103 mm2/s in showing recurrent tumours was 100% and the specificity was 77.78%. The sensitivity of b-400 values lower than 2.1 × 103 mm2/s in showing recurrent tumours was 80% and the specificity was 96.3%. The sensitivity of b-800 values lower than 2.26 × 103 mm2/s in showing recurrent tumours was 100% and the specificity was 88.89%. The sensitivity of b-1000 values lower than 2 × 103 mm2/s in showing recurrent tumours was 93.3% and the specificity was 92.5%. CONCLUSIONS: The ADC values obtained from diffusion-weighted images have high sensitivity and specificity in differentiating recurring soft tissue sarcomas during monitoring after treatment from postoperative changes.

Role of fine needle aspiration cytology in the diagnosis of soft tissue tumours.

Fine needle aspiration cytology (FNAC) is a widely accepted safe, simple and rapid diagnostic procedure used in the examination of neoplastic and non-neoplastic lesions of various locations. Since its introduction, FNAC has developed into an effective diagnostic tool practiced in a large majority of medical centres evaluating and treating oncological patients. The role of FNAC has been limited in the examination of primary soft tissue lesions, however, as many physicians working in this area recommended against using FNAC. An increasing use of minimally invasive diagnostic procedures in the last decade has resulted in a better acceptance of FNAC as a first-line approach or as a complementary tool to core needle biopsy in the diagnosis of musculoskeletal lesions. This review discusses the role and value of FNAC in the evaluation and treatment of soft tissue tumours based on the experience gathered over the course of 48 years at the Sarcoma Center in Lund, Sweden. FNAC reports most often provide diagnostic information allowing the initiation of treatment or, when definitive diagnosis cannot be rendered from a cytological examination, guiding the continued diagnostic investigation. The main advantages of soft tissue FNAC are good sensitivity and specificity, low morbidity, speed of diagnosis, and low cost/benefit ratio. The most important disadvantages stem from limited experience in cytological diagnosis of soft tissue tumours and a lack of standardised and uniform reporting system for soft tissue FNAC.

Cytomorphological spectrum, including immunohistochemical results of 16 cases of clear cell sarcoma of soft tissue, along with positive EWSR1 gene rearrangement result in two cases.

OBJECTIVES: To describe the cytopathological features of clear cell sarcomas (CCSs), including immunohistochemical and molecular results, the latter in selected cases. METHODS: Sixteen consecutively diagnosed cases of CCS of soft tissue, over 6-year duration were included. Fine needle aspiration cytology was performed for primary diagnosis in three and for recurrent/metastatic lesions in 12 cases. Cytopathological features in 16 cases (conventional Papanicolaou- and May-Grünwald Giemsa-stained smears) were critically analysed. Corresponding histopathological and immunostained sections were available in 15 cases. Two cases were tested for EWSR1 gene rearrangement by fluorescence in-situ hybridisation. RESULTS: Sixteen tumours occurred in patients with age ranging from 18 to 56 years (median = 33.5); M: F ratio = 1:1; in deep soft tissues, mostly in extremities. Primary cytopathological diagnosis (3 cases) was CCS with a differential diagnosis of melanoma (1 case) and poorly differentiated malignant tumour (2 cases). On review, smears were predominantly hypercellular (n = 14), invariably composed of monomorphic appearing epithelioid/polygonal cells (n = 16), including spindle cells (n = 6); mostly singly scattered (n = 16), in loose clusters (n = 12); with prominent nucleolisation (n = 16); granular to vacuolated, well-defined cytoplasm (n = 12), binucleation/multinucleation (n = 9); mitoses (n = 6); sudden anisonucleosis; racquet-shaped cells (n = 3), against a tigroid background (n = 2), along with focal intracytoplasmic pigment deposition (n = 2). Immunohistochemically, tumour cells were positive for S-100P (15/15), HMB-45 (15/15) and melan-A(6/12). Two cases tested for EWSR1 rearrangement displayed red-green split signals. CONCLUSIONS: This constitutes one of the largest series describing the cytomorphological spectrum of CCS of soft tissue. Certain features, such as singly scattered monomorphic, epithelioid cells with prominent nucleolisation are useful diagnostic clues. Immunohistochemical stains are necessary and molecular testing is further helpful in reinforcing a diagnosis in certain cases. A correct diagnosis has crucial treatment implications.

Cutaneous leiomyosarcoma: dermal and subcutaneous.

BACKGROUND AND OBJECTIVES: Leiomyosarcoma of skin (LMS) can be sub-classified on pathology appearances as Dermal or Subcutaneous. The aim of this study was to provide treatment recommendations for these uncommon tumours. METHODS: A retrospective review of all patients with dermal and subcutaneous leiomyosarcoma managed at the Peter MacCallum Cancer Centre, Australia from January 2003 to December 2018 was performed. Eighty-three patients were identified (64 dermal leiomyosarcoma, 19 subcutaneous leiomyosarcoma). RESULTS: Subcutaneous leiomyosarcoma were larger (median size 14 mm dermal, 49 mm subcutaneous, P = 0.01). No patient with a dermal leiomyosarcoma developed metastatic disease compared to 4 of the 19 subcutaneous leiomyosarcoma (5-year overall survivals, 98% and 88%, respectively, P = 0.03). The most common site of metastasis was to the lung. No difference in risk of local recurrence was apparent (5-year recurrence-free survivals were 85% and 78%, respectively, P = 0.17). Adjuvant radiotherapy was used in 16 (25%) dermal leiomyosarcoma patients and 13 (68%) subcutaneous leiomyosarcoma patients (P < 0.001). Local recurrence was uncommon in both tumour subtypes when patients received definitive surgical excision (minimum histological margins of 10 mm as per institutional protocol) regardless of whether radiotherapy was used. The 5-year local recurrence-free survival for dermal leiomyosarcoma treated with radiotherapy was 93% versus 83% without radiotherapy (P = 0.7) and for subcutaneous leiomyosarcoma was 69% and 100%, respectively (P = 0.9). CONCLUSIONS: Dermal leiomyosarcoma have an excellent prognosis, particularly after definitive surgical excision with margins of at least 10 mm. Subcutaneous leiomyosarcoma has poorer outcomes and should be managed by wider excision and considered for adjuvant radiotherapy.

Primary malignant ossifying fibromyxoid tumour of the bone. A clinicopathologic and molecular report of two cases.

OBJECTIVE: To report the exceptional occurrence of ossifying fibromyxoid tumour (OFMT) as a primary bone lesion. OFMT is a rare soft tissue tumour of uncertain differentiation and variable malignant potential, that occurs in adults with a slight male predominance. It is typically located in the subcutis or in the skeletal muscles of the extremities, followed by trunk or head and neck. METHODS: Two cases of OFMT proven to arise from bone are presented. The first is a 65-year old female with a history of rib "osteosarcoma", presenting with an inferior lobe left lung mass. The second is a man with a lytic lesion of the 5th cervical vertebra that recurred shortly after resection. Following H&E and immunohistochemical examination, tumour samples were analysed by NGS and by break-apart FISH to detect rearrangement of the PHF1 and TFE3 genes. RESULTS: PHF1 gene-rearrangement was identified by FISH on both the primary and the metastatic lesion of first patient. NGS identified a PHF1(intron1) and EPC1 (exon 10) fusion transcript later confirmed by positive PHF1 rearrangement on FISH in the second case. CONCLUSIONS: The demonstration of PHF1 gene rearrangements represents a fundamental ancillary diagnostic test when presented with challenging examples of OFMT.

Revisiting the WHO classification system of soft tissue tumours: emphasis on advanced magnetic resonance imaging sequences. Part 1.

The World Health Organisation (WHO) classification categorises musculoskeletal soft tissue tumours (STT) based on their similarity to normal adult tissue. The most recent WHO classification provides an updated scheme that integrates biological behaviour as a distinguishing feature in each subcategory; STTs are further subdivided as benign, intermediate (locally aggressive or rarely metastasising), and malignant. Although malignant STTs are infrequent in routine orthopaedic radiology practice, musculoskeletal radiologists must be familiar with the imaging appearance of malignant STTs and distinguish them from their benign counterparts for appropriate management. Magnetic resonance imaging (MRI) is the ideal modality for the detection, characterisation, and local staging of STT. This review will discuss the most recent updates to the WHO classification of STT that are relevant to radiologists in a routine clinical practice with MRI correlation. The utility of advanced MRI sequences such as diffusion weighted imaging, dynamic contrast enhanced sequences, and magnetic resonance spectroscopy to provide insight into the biological behaviour of various STTs is highlighted.

Clinicocytopathological spectrum, including uncommon forms, of nine cases of chordomas with immunohistochemical results, including brachyury immunostaining: A single institutional experience.

OBJECTIVES: To present clinical and cytopathological features of nine cases of chordomas, diagnosed over 9 years and confirmed by brachyury (T) immunostaining. METHODS: Conventional cytological smears, stained with Papanicolaou and May-Grünwald Giemsa, along with corresponding histopathological (n = 8) and immunostained sections (n = 8) were reviewed. Immunohistochemical staining was performed on tissue sections by polymer detection technique. RESULTS: Nine tumours occurred in seven males and two females, with age ranging from 36 to 72 years (average = 58.7), in the sacrum (seven) and spine (two). On fine needle aspiration cytology, five cases were either diagnosed with or diagnosed with a suggestion of a chordoma, while three cases were diagnosed with chordoma as a differential diagnosis. On review, smears were moderately cellular, comprising myxoid stroma (9/9), epithelioid cells (9/9), physaliphorous cells (8/9), including binucleation (7/9), prominent nucleolisation (2/9), pleomorphic cells (2/9) and intranuclear inclusions (3/9). Immunohistochemically, tumour cells expressed cytokeratin (4/4), pan cytokeratin (4/4), epithelial membrane antigen (8/8), S100 protein (6/8) and brachyury (8/8). Five patients underwent surgical excision, including two who underwent adjuvant radiotherapy (RT) and four patients who underwent RT. During follow-up (n = 8), a single patient developed recurrence and another presented with metastatic lesions. Finally, five patients were alive with disease (7-53 months); a single patient was free of disease (4 months), and two patients died of disease; the latter cases displayed pleomorphic cells and intranuclear inclusions. CONCLUSIONS: Chordomas can be primarily diagnosed by fine needle aspiration cytology in a typical clinicoradiological setting with a combination of key cytomorphological features. Pleomorphic cells and intranuclear inclusions are associated with a relatively aggressive subtype. An exact diagnosis has treatment implications and requires confirmation by brachyury immunostaining.

Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract are genetically different from nodular fasciitis and lack USP6, ROS1 and ETV6 gene rearrangements.

AIMS: Pseudosarcomatous myofibroblastic proliferations of the genitourinary tract have a debatable relationship with inflammatory myofibroblastic tumour (generally lacking ALK rearrangement); however, they share several overlapping features with nodular fasciitis of soft tissue. As rearrangement of the USP6 gene has been recently recognised as a recurrent alteration in soft tissue nodular fasciitis, and several other alternative gene fusions have been recently recognised in inflammatory myofibroblastic tumour, the aim of this study was to investigate whether USP6, ROS1 or ETV6 rearrangements were present in these lesions (12 cases). METHODS AND RESULTS: Fluorescence in-situ hybridisation analysis was performed by the use of bacterial artificial chromosome-derived break-apart probes against USP6, ROS1, and ETV6. Two cases with adequate genetic material from recent paraffin tissue blocks were also tested by use of a solid tumour gene fusion detection assay via next-generation sequencing, targeting >50 known genes involved in recurrent fusions. None of the genitourinary pseudosarcomatous myofibroblastic proliferations was found to harbour USP6 (0/12), ROS1 (0/8) or ETV6 (0/7) rearrangements, and no gene fusions were detected in two cases studied by sequencing. CONCLUSIONS: Despite overlap in histological and immunohistochemical features between pseudosarcomatous myofibroblastic proliferation and nodular fasciitis, these tumours lack the recently recognised USP6 rearrangements that occur in nodular fasciitis, as well as alternative fusions found in ALK-negative inflammatory myofibroblastic tumours. At present, this diagnosis remains based primarily on clinical, histological and immunohistochemical features.

Intramuscular myxoma: clinical and surgical observation notes on eleven cases.

PURPOSE: Intramuscular myxoma (IM) is a benign, soft tissue neoplasm of mesenchymal origin. We report our experience with this tumour. METHOD: This clinical study comprised 11 cases of IM that were operated on between March 2008 and June 2016. Tumour location and size, results of pre-operative radiological studies, preop-erative biopsies, pathology examinations, applied surgical method and post-operative complications were reported for all patients. RESULTS: In total, nine patients with 11 IMs with a mean age of 60.0 years were assessed. Mean follow-up was 39.2 months. Tumours were located in the right thigh (5 patients, 7 IM), left gluteal area (2 patients, 2 IM), right gluteal area (1 IM) and left thigh (1 IM) ranging from 2 × 1 cm to 10 × 17 cm Pre-operative radiological diagnoses were cystic lesion, abscess, bursitis, fibrosarcoma, fibroma, lipoma, malign mesenchymal tumour and IM. Pre-operative biopsy was performed for five cases. All tumours were removed via simple excision and were pathologically consistent with IM. No complication or recurrence was observed during the follow-up period. CONCLUSION: IM is a relatively rare benign tumour, the pre-operative diagnosis of which using radiological and clinical methods is quite difficult, creating pre-operative diagnostic confusion. It is generally diagnosed by microscopic examination. Simple excision with a small margin of surrounding tissue is considered to be sufficient for its treatment.

Does size reliably predict malignancy in soft tissue tumours?

PURPOSE: In this retrospective study we examined whether size is a viable marker of tumour malignancy in soft tissue masses (STM) and if the ratio of width and length (RALD) of an STM reflects tumour biology more accurately. METHODS: Measurements of maximal lesion size and perpendicular diameter were performed in available MRI and ultrasonography studies of 212 patients (mean age 54.4 ± 17.2 years, male:female 1:1.12) with a histologically verified diagnosis. RESULTS: Overall, 28.2 % of lesions were malignant, 11.1 % intermediate, and 58.8 % benign. Size alone was a weak predictor of malignancy in STMs (sensitivity 68.8 %, specificity 50.3 %, positive predictive value [PPV] 44.0 %, negative predictive value [NPV] 80.4 %). RALD showed better discriminatory power with greater separation between benign and malignant entities and higher values for sensitivity (83.6 %), specificity (53.6 %), and NPV (89.0 %). A weighted combination of size, age and RALD improved diagnostic power, demonstrating higher values for sensitivity (77.0 %), specificity (80.1 %), PPV (61.0 %), and NPV (89.6 %). CONCLUSIONS: Size should not be used alone to estimate an STM's malignancy. RALD better reflects a lesion's growth pattern and a combination of age, size, and RALD helps to discriminate more accurately between benign, intermediate, and malignant entities. These findings should help to estimate easily whether a newly found STM is benign or malignant prior to further workup. KEY POINTS: •Size does not reliably differentiate between benign, intermediate, and malignant tumours •The R ALD (ratio of lateral to axial diameter) improves diagnostic confidence •When combined with age and size, STM differentiation was further enhanced •These measurements can aid in earlier detection of sarcomas.

Dermatofibroma-like granular cell tumour: a potential diagnostic pitfall.

Dermatofibroma-like granular cell tumour (GCT) is a rare entity, with only two cases having been described so far. We report another case in a 62-year-old woman, discuss histopathological features, and review other tumours in which granular changes have been observed. Our tumour was composed predominantly of oval-to-spindle granular cells with prominent nucleoli, arranged in short fascicles and storiform pattern, infiltrating around collagen bundles. Immunohistochemical analysis with antibodies against CD31, CD56, CD68, CD117, S-100 protein, inhibin, calretinin, EMA, p53 and MIB-1 was performed, showing expression of CD56, CD68, S-100 protein, inhibin and calretinin. The diagnosis of atypical dermatofibroma-like GCT was made.