Cytomorphology of lipomatous tumors of soft tissue

Soft Tissue Fine-Needle Aspiration: Current and Future Impact on Patient Care

Soft tissue neoplasms pose many diagnostic challenges on fine-needle aspiration (FNA), owing largely to their rarity, large number of entities, and histologic diversity. Advances in ancillary testing now allow detection of the characteristic immunophenotypes and molecular alterations for many neoplasms and include reliable surrogate immunohistochemical markers for underlying molecular events that are highly efficient in small biopsies. A morphology-based framework is recommended to guide appropriate differentials and judicious selection of ancillary tests for small biopsies. The accurate diagnosis of soft tissue tumors is crucial for patient management and prognostication, with many potential implications in this era of precision medicine.

Pleomorphic liposarcoma: A clinicopathologic study of 20 FNA cases

BACKGROUND

Pleomorphic liposarcoma (PLPS) is the least common but most aggressive of all forms of liposarcoma (LPS). Its diagnosis relies on the recognition of pleomorphic lipoblasts (PLBs), whose numbers vary considerably. Because few large fine-needle aspiration (FNA) biopsy studies exist, the authors review their experience with PLPS.

METHODS

The authors' cytopathology files were searched for PLPS with histopathologic verification. FNA biopsy smears were performed via standard techniques.

RESULTS

Twenty cases from 20 patients (male/female ratio, 2.3/1; age range, 22-77 years; mean age, 58 years) met the inclusion criteria. All had tissue confirmation. Biopsy sites included the following: thigh (11 [55%]), upper extremity (4 [20%]), axilla (2 [10%]), neck (1 [5%]), chest wall (1 [5%]), and mediastinum (1 [5%]). Aspirates were from primary (17 [85%]), locally recurrent (2 [10%]), and metastatic neoplasms (1 [5%]). The FNA diagnoses were PLPS (10 [50%]), myxofibrosarcoma (4 [20%]), LPS (2 [10%]), sarcoma (2 [10%]), and high-grade malignant neoplasm (2 [10%]). Smears showed thick cell clusters and dissociated single forms. Pleomorphic, epithelioid, and bizarre cell/nuclear shapes were common. PLBs were absent, rare, or unnoticed in 45%. In 25%, smears dominated by myxoid stroma were diagnosed as high-grade myxofibrosarcoma or myxoid LPS. Ancillary testing performed in 5 cases had limited diagnostic efficacy.

CONCLUSIONS

FNA biopsy of PLPS, although able to successfully recognize malignancy, suffers from a sampling bias due to an inability to capture or recognize PLBs in a significant proportion of cases secondary to the heterogeneous composition of this neoplasm.

Comparative cytological and histological assessment of 828 primary soft tissue and bone lesions, and proposal for a system for reporting soft tissue cytopathology

Introduction

The aim of the study was to evaluate the diagnostic utility of fine needle aspiration (FNA) cytology and core needle biopsies (CNBs) in a series of primary soft tissue and bone lesions and to test a possible system for reporting results of FNA cytology of soft tissue lesion.

Methods

This retrospective study encompassed 828 primary soft tissue and bone lesions, analysed with FNA, CNB and/or surgical specimen in order to perform sensitivity/specificity as well as accuracy analyses. The series was then used to test a system for reporting soft tissue cytopathology with six categories and the risk of malignancy in each category was calculated.

Results

With a malignant diagnosis defined as positive test result, FNA and CNB analysis showed sensitivity of 87% and 94%, respectively, and specificity of 89% and 95%, respectively. FNA and CNB analyses identified the correct histopathological entity of the examined lesion in 55% and 66%, respectively. The risk of malignancy within the tested categories was non‐diagnostic 42%, non‐neoplastic 0%, atypia of unknown significance 46%, neoplasm benign 3%, neoplasm of unknown malignant potential 27%, suspicious for malignancy 72% and malignant 97%.

Conclusion

FNA cytology is a suitable tool to determine the malignant potential of a sampled soft tissue/bone lesion but is inferior to CNB in defining the correct entity. A standardised reporting system might improve the clinical management of patients with soft tissue tumours examined primarily by FNA cytology.

The study evaluated the diagnostic utility of fine needle aspiration cytology and core needle biopsies in 828 primary soft tissue and bone lesions. In a second step, a possible system for reporting results of fine needle aspiration cytology of soft tissue lesion was tested.

Mediastinal sarcomas: experience using fine needle aspiration cytopathology

Fine needle aspiration (FNA) cytology is a sparsely used diagnostic method in the evaluation of mediastinal sarcomas in most medical centers worldwide with most literature citations regarding this category of malignancies consisting of small series and individual case reports. Most of these published studies highlight vascular sarcomas such as epithelioid hemangioendothelioma, and angiosarcoma, various subtypes of liposarcoma including well-differentiated liposarcoma, myxoid liposarcoma, and pleomorphic liposarcoma, malignant peripheral nerve sheath tumor, and sarcomas of uncertain differentiation, primary synovial sarcoma and the Ewing sarcoma family of tumors. This paucity of cytopathology reports regarding mediastinal sarcomas is in marked contrast to the almost daily application of endobronchial ultrasound (EBUS)-guided FNA biopsy for sampling mediastinal lymph nodes and mediastinal masses for primary and metastatic carcinomas which, of course, are considerably more common that any type of sarcoma in this location. EBUS, endoscopic ultrasound-guided (EUS) needle biopsy, and percutaneous image-guided biopsy using either core needle, fine-needle, or both can serve a potentially useful role for diagnostic sampling of mediastinal sarcomas, be they primary or metastatic. This review catalogues much of the published data regarding FNA cytopathology and its application to mediastinal sarcomas. An attempt is made to primarily highlight case series rather than individual case reports; however, due to the paucity of these, case reports are cited and discussed where appropriate.

Applications of Ancillary Testing in the Cytologic Diagnosis of Soft Tissue Neoplasms

Soft tissue neoplasms are diagnostically challenging, although many advances in ancillary testing now enable accurate classification of fine-needle aspiration biopsies by detection of characteristic immunophenotypes (including protein correlates of molecular alterations) and molecular features. Although there are many useful diagnostic immunohistochemical markers and molecular assays, their diagnostic utility relies on correlation with clinical and morphologic features, judicious application, and appropriate interpretation because no single test is perfectly sensitive or specific. This review discusses applications of ancillary testing for commonly encountered soft tissue neoplasms in cytopathologic practice in the context of a pattern-based approach.

Hypercellular round cell liposarcoma: A comprehensive cytomorphologic study and review of 8 cases

Background:

Myxoid and round cell liposarcomas (RCL) are low and high-grade counterparts of a common subtype of liposarcomas (LPS), representing a histologic continuum.

Aims:

The aim was to study the cytomorphology of hypercellular RCL and to look for features that differentiate RCL from other sarcomas displaying round cells with myxoid change.

Materials and Methods:

Eight cases of hypercellular RCL were identified retrospectively in which round cell component constituted greater than 75% of the area. Cytomorphological features were studied in detail.

Results:

Four cases were predominantly composed of round cells, out of which 2 were entirely composed of round cells. Myxoid metachromatic stroma was absent in 2 cases, while it was present in ample amounts in the remaining 6 cases. Spindle cells were completely absent in 5 cases and lipoblasts were observed in a single case of RCL. Plexiform vascular capillaries were seen in 4 cases. Adherence of neoplastic round cells around thin capillaries (ANAC) was observed in 7 cases.

Conclusions:

Plexiform capillary plexus and ANAC should be separately evaluated. The latter feature is the most consistent one, and is an important clue to the adipocytic nature of the neoplasm when hypercellular round cell areas are aspirated. Confident diagnosis of hypercellular RCL can be made on the basis of this feature. Lipoblasts, although specific, are seen in few cases. The rest of the features are nonspecific and useful only in combination.

Myxoid liposarcoma: Fine-needle aspiration cytopathology in the molecular era. A report of 24 cases

INTRODUCTION

Application of fine-needle aspiration (FNA) biopsy to soft tissue tumors remains underutilized in North America. Myxoid liposarcoma (LPS), the second most common subtype of LPS, is characterized primarily by t(12;16)(q13;p11) which is amenable to FISH analysis using a break-apart probe for DDIT3. Little is known regarding FISH testing for DDIT3 on cytologic specimens. We report our FNA experience with myxoid LPS and application of this molecular probe.

MATERIALS AND METHODS

Specimens retrieved from our cytology database used search codes for myxoid LPS. Tissue files were searched for any cases with corresponding FNA biopsies. FNA biopsy was performed using a standard technique.

RESULTS

From 24 FNA cases of myxoid LPS (mean age = 52 years), a specific diagnosis was made in 87.5%. Two cases were diagnosed as spindle/round cell neoplasm, and 1 as suspicious for myxoid LPS. There were 2 false positive diagnoses and no false negatives. Nearly all cases arose in the extremities; thigh being most common. Principal cytologic features consisted of discrete myxocellular microfragments, a plexiform capillary pattern, and variable number of univacuolated lipoblasts. Uniformly banal ovoid nuclei were randomly scattered within myxocellular microfragments. FISH analysis for DDIT3 rearrangement from unstained smears and/or cell-block was positive in 13 cases, and unsuccessful in 3, with no false positive/false negative results.

CONCLUSION

Myxoid LPS is diagnosable in a high percentage of cases using FNA biopsy alone. Confirmatory FISH analysis for DDIT3 is not only possible, but also valuable for correctly recognizing this neoplasm.

Pleomorphic liposarcoma: a cytologic study of five cases

Pleomorphic liposarcoma represents one of the rarest variants of liposarcoma. It has a poor prognosis and unlike other variants of liposarcoma, lacks a molecular or genetic signature. Histologic studies of pleomorphic liposarcoma have defined this lesion as a high grade sarcoma, which contains a variable number of lipoblasts. We describe the cytologic features of five cases of pleomorphic liposarcoma, all of which had histologic confirmation. We consistently identified numerous lipoblasts as well as micro and macrovesicular fat vacuoles in the background of cellular, pleomorphic sarcomatoid neoplasms. The appearance of the aspirates differs substantially form other variants of liposarcoma.

A 20-year-old man with large gastric lipoma--imaging, clinical symptoms, pathological findings and surgical treatment

A broad search of the available literature yielded no other report of gastric lipoma of that size (13.5 x 6.5 x 4.5 cm) at this early age. The patient (a 20-year-old man with giant lipoma in the anterior gastric wall) presented with haematemesis and melena after excessive alcohol consumption. Gastric resection was performed. At 5-year follow up the patient is healthy and doing well. Epidemiology of gastric lipoma, the differential diagnosis, means of diagnosis and treatment are discussed.

Two Cases of Retroperitoneal Liposarcoma Diagnosed Using Endoscopic Ultrasound-Guided Fine-Needle Aspiration (EUS-FNA)

This report describes our experience with two cases that were ultimately diagnosed as retroperitoneal liposarcoma using endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). Case 1 is that of a 54-year-old woman with chief complaints of nausea and abdominal distention. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large (15 cm diameter) tumor, which was significantly compressing the stomach and apparently occupied the entire left abdominal cavity. Although advanced primary gastrointestinal stromal tumor (GIST) or retroperitoneal tumor was inferred as the differential diagnosis, a definitive diagnosis was difficult using imaging alone. After EUS-FNA was done, the tumor was diagnosed histopathologically as high-grade liposarcoma. Case 2 is that of a 73-year-old man. Abdominal ultrasonography and CT showed a 6 cm diameter tumor within the pelvic cavity. The tumor had high MRI signal-intensity on both T1 and T2 images. Endorectal EUS showed a hyperechoic mass. The images suggested lipoma or liposarcoma containing lipoma-like components. Myxoid liposarcoma was revealed by subsequent EUS-FNA. Performing EUS-FNA was clinically useful for determining the subsequent therapeutic strategy in these cases where a tumor of unknown origin existed in the retroperitoneum.

Atypical lipomatous tumors of the face: a controversial issue

We reviewed the topic of atypical lipomatous tumors including definition, diagnosis and management, with special emphasis on head and neck location and to report on the management of a rare case located in the temporalis muscle. Atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLS) are rarely reported in the head and neck. Their behavior dictates a complete resection. Resection with a safety margin is sometimes needed according to the histological characteristics. Tumors located to the masticator space can be accessed through a mucosal approach achieving relative safety to the facial nerve. ALT constitute a group of tumors of a borderline behavior. Their management can be affected by some histological criteria and by their location in the head and neck region where vital structures can be affected.

Lipoma of the deep lobe of the parotid gland: report of 3 cases

Since lipomas are common soft-tissue neoplasms in other regions of the body, they are found only rarely in the parotid gland and are, therefore, often not considered in the initial differential diagnosis of parotid gland tumours. Even rarer are lipomas arising in the deep lobe of the parotid gland with only 6 cases presented in the literature. Lipomas originating in the parapharyngeal space are also extremely rare. When there is any suspicion, computed tomography and especially magnetic resonance imaging are of high diagnostic value. Fine-needle aspiration cytology seems not to contribute much to an accurate diagnosis. None of these preoperative examinations allows an absolute reliable distinction between a lipoma and a liposarcoma. The preferred treatment is complete surgical excision which will minimize the possibility of a recurrence and will also lead to a definitive diagnosis. We report 3 patients with a lipoma of the deep lobe of the parotid gland, extending into the parapharyngeal space, and discuss differential diagnosis and radiological features of lipomas in this rare location.