Nodular fasciitis: A frequent diagnostic pitfall on fine-needle aspiration

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.

Pitfalls in soft tissue cytopathology

Fine needle aspiration biopsy (FNAB) is a diagnostic modality for the evaluation of suspicious soft tissue masses. Despite its reasonable sensitivity, specificity and positive predictive value in differentiating benign from malignant neoplasms, the exact subtyping of the primary soft tissue tumours can be challenging. Certain tumours constitute "pitfalls" and add to the diagnostic challenge. This review provides a detailed account of the diagnostic challenges in soft tissue cytopathology, including pitfalls and, more importantly, the ways to overcome these challenges by integrating clinical details, key cytomorphological features and judicious application of ancillary techniques.

Development of clinical and magnetic resonance imaging-based radiomics nomograms for the differentiation of nodular fasciitis from soft tissue sarcoma

BACKGROUND

Accurate differentiation of nodular fasciitis (NF) from soft tissue sarcoma (STS) before surgery is essential for the subsequent diagnosis and treatment of patients.

PURPOSE

To develop and evaluate radiomics nomograms based on clinical factors and magnetic resonance imaging (MRI) for the preoperative differentiation of NF from STS.

MATERIAL AND METHODS

This retrospective study analyzed the MRI data of 27 patients with pathologically diagnosed NF and 58 patients with STS who were randomly divided into training (n = 62) and validation (n = 23) groups. Univariate and multivariate analyses were performed to identify the clinical factors and semantic features of MRI. Radiomics analysis was applied to fat-suppressed T1-weighted (T1W-FS) images, fat-suppressed T2-weighted (T2W-FS) images, and contrast-enhanced T1-weighted (CE-T1W) images. The radiomics nomograms incorporating the radiomics signatures, clinical factors, and semantic features of MRI were developed. ROC curves and AUCs were carried out to compare the performance of the clinical factors, radiomics signatures, and clinical radiomics nomograms.

RESULTS

Tumor location, size, heterogeneous signal intensity on T2W-FS imaging, heterogeneous signal intensity on CE-T1W imaging, margin definitions on CE-T1W imaging, and septa were independent predictors for differentiating NF from STS (P < 0.05). The performance of the radiomics signatures based on T2W-FS imaging (AUC = 0.961) and CE-T1W imaging (AUC = 0.938) was better than that based on T1W-FS imaging (AUC = 0.833). The radiomics nomograms had AUCs of 0.949, which demonstrated good clinical utility and calibration.

CONCLUSION

The non-invasive clinical radiomics nomograms exhibited good performance in the differentiation of NF from STS, and they have clinical application in the preoperative diagnosis of diseases.

An update on selected cutaneous (myo) fibroblastic mesenchymal tumors

Cutaneous (myo)fibroblastic tumors constitute a group of tumors with overlapping clinicopathological features and variable biologic behavior. In the present review we focus on the histomorphology, immunohistochemical profile and molecular background of the following entities: dermatofibrosarcoma protuberans (DFSP), CD34-positive fibroblastic tumor (SCD34FT), myxoinflammatory sarcoma (MIFS), low-grade myofibroblastic sarcoma, solitary fibrous tumor and nodular fasciitis. Although some of these entities typically arise in deep-seated locations, they may occasionally present as cutaneous/superficial tumors and might be challenging to recognize. This review covers in depth the latest advances in molecular diagnostics and immunohistochemical markers that have significantly facilitated the correct classification and diagnosis of these neoplasms.

Pitfalls in the cytological diagnosis of nodular fasciitis: A report of two cases

Cytological diagnosis of nodular fasciitis can be challenging. The main features on cytological smears are bland, round to ovoid cells with fuzzy cytoplasmic processes in a background of focal myxoid change. The cytological features of two cases of nodular fasciitis are described here, along with the cytological differentials.

Nodular Fasciitis of the Nose and External Auditory Canal: Two Rare Case Reports

Nodular fasciitis(NF) is a proliferative disease of fibroblasts and myofibroblasts that generally affects subcutaneous tissue, muscle tissue, and fascia. NF usually occurs in young adults aged 20-40 and is more common in the upper extremities and relatively rare in the region of the head and neck. Here, we report on two patients with NF in the ear and nose. Under general anesthesia, the masses of NF were completely resected along the safety margin. The patients recovered well after surgery and there was no recurrence after more than half a year of follow-up.

Approach to Fine Needle Aspiration of Giant Cell-rich Tumors of Soft Tissue

Giant cells may be found in a wide variety of reactive and neoplastic soft tissue lesions. Because of their distinct histomorphology, they often stand out in procured samples such as fine needle aspirates. The giant cells themselves may be benign or neoplastic. However, the presence, type, and quantity of giant cells are usually not specific and in some cases can even be misleading when making a diagnosis. The aim of this review is to guide the practicing cytopathologist in narrowing their differential diagnosis when encountering one of these challenging giant cell-rich lesions of the soft tissue.

Approach to FNA of Myxoid Soft Tissue Tumors

Myxoid tumors of the soft tissue encompass a group of heterogenous tumors that are characterized by the presence of abundant extracellular myxoid or chondromyxoid matrix material. Fine needle aspiration (FNA) is variably used for diagnosing primary, recurrent, and metastatic myxoid soft tissue tumors. The spectrum of myxoid soft tissue tumors encountered in practice ranges from benign lesions such as simple ganglion cysts to high-grade malignant sarcomas such as myxofibrosarcoma. These myxoid tumors have clinical, cytologic, and histologic overlap. Therefore, making an accurate diagnosis by FNA alone is challenging. Despite this challenge, using a systematic cytomorphologic approach and ancillary studies, an accurate diagnosis is feasible in the majority of cases. This article provides a systematic approach to diagnosing myxoid soft tissue tumors by FNA along with a review of the literature.

Mesenchymal neoplasms of the parotid gland and parapharyngeal space: an FNA cytologic study of 22 nonlipomatous tumors

BACKGROUND

Mesenchymal neoplasms of the parotid gland (PG) and para-pharyngeal (PP) space are distinctly uncommon. Fine-needle aspiration (FNA) biopsy experience with nonlipomatous neoplasms from this site is reviewed.

METHODS

Cytopathology and surgical pathology files were examined for mesenchymal PG and PP space neoplasms. FNA biopsy was performed using standard technique.

RESULTS

Twenty-two PG and/or PP aspirates from 20 adults (male:female = 1.1:1; age range, 19-84 years, mean age, 50 years) and a 10-week-old infant met inclusion criteria. Biopsy sites included PG (17, 77%) or PP space (5, 23%). Five of 6 malignant neoplasms (83%) were called malignant cytologically. Only 7 of 11 (63%) benign neoplasms were recognized as a benign neoplasm. None of 5 solitary fibrous tumor (SFT) cases were correctly recognized. Conversion to the Milan classification showed 8 (36%) FNA cases diagnosed as benign neoplasm, 6 (27%) malignant neoplasm, 4 (18%) neoplasm of uncertain malignant potential, 2 (9%) nondiagnostic, and single cases of suspicious for malignancy and nonneoplastic. There was 1 false-positive and no false-negative FNA diagnoses. Ancillary testing in 10 (45%) aspirates helped substantiate a correct specific diagnosis in 3 malignant and 3 benign cases.

CONCLUSIONS

FNA biopsy of nonlipomatous mesenchymal SG neoplasms is particularly challenging. Less than half (9 of 11, 41%) had specific FNA diagnoses that correctly matched the tissue diagnoses or clinical outcome. Accurate Milan categorization was superior for malignant neoplasms (5 of 6, 83%) in contrast to benign neoplasms (7 of 11, 63%), or neoplasms of uncertain malignant potential (SFT) (2 of 5, 40%).

Concomitant spinal dural arteriovenous fistula and nodular fasciitis in an adolescent: case report

Background

Spinal dural arteriovenous fistula (SDAVF) usually occurs during the 4^th to 6^th decades of life, and adolescent SDAVF is rarely reported. SDAVF arising around a tumor is also rare, and reported tumors are mostly schwannoma and lipoma.

Case presentation

We reported a 16-year-old male presented with progressive weakness and numbness of lower limbs for 3 months. A SDAVF was found, which was fed by right radicular arteries from segmental artery at L2 level and drained retrogradely into perimedullary veins. A concomitant spinal extradural nodular fasciitis at right L1/L2 intervertebral foramen was also noted. The SDAVF was completely obliterated by endovascular treatment and the tumor was debulked. The patient recovered well after the procedures.

Conclusions

Our case report suggests SDAVF can occur in adolescent. The concomitant presence with a nodular fasciitis indicates that although it usually arises in subcutaneous tissue but can rarely form on the dura of spine.

Giant cell tumor of soft tissue: FNA cytopathology of 4 cases, review of the literature, and comparison with giant cell tumor of bone

BACKGROUND

The cytopathology of a giant cell tumor of soft tissue (GCT-ST), a fibrohistiocytic neoplasm distinct from other giant cell-rich soft tissue tumors, is rarely reported. The authors report their experience with a series of 4 GCT-ST fine-needle aspiration (FNA) biopsy cases and compare them with a set from giant cell tumors of bone (GCTBs).

METHODS

The authors' cytopathology files were searched for GCT-ST examples with histopathologic confirmation. FNA biopsy smears were performed and examined with standard techniques.

RESULTS

Four cases of GCT-ST presenting as a primary soft tissue mass from 4 patients (3 males and 1 female; age range, 28-75 years, mean age, 53 years) were retrieved. FNA sites included the anterior tibia, buttock, shoulder, and upper back. Three cases were interpreted as suspicious for sarcoma radiographically. The specific diagnoses were atypical giant cell tumor of tendon sheath, suspicious for GCT-ST, atypical myxoid lesion with giant cells, and benign with osteoclast-like giant cells (OLGCs). No case was interpreted as malignant. Aspirates consisted of mononuclear polygonal cells, spindled fibroblast cell clusters, and large OLGCs to the near exclusion of other cell types. OLGCs possessed 10 or more nuclei per cell. A comparison with GCTB aspirates and single case reports from the literature showed comparable cytomorphology.

CONCLUSIONS

GCT-ST FNA smears mimic those of GCTBs containing a limited population of uniform spindle cell clusters, single dispersed polygonal cells, and cytologically banal OLGCs. GCT-ST should be considered in the differential diagnosis of aspirates containing numerous osteoclast-like giant cells.

A rare case of maxillary nodular fasciitis: Case report and short literature review

Nodular fasciitis has to be considered as an option in the presence of a solitary, rapidly growing mass even in older adults. When possible, direct surgery should be preferred to FNAC, particularly in the older adults because of high misdiagnostic risk.

MR imaging features and a redefinition of the classification system for nodular fasciitis

To analyze magnetic resonance imaging features of nodular fasciitis and redefine the system for classifying this class of lesions.Twenty-seven patients with nodular fasciitis and 71 patients with other soft tissue lesions who underwent surgery or biopsy were retrospectively analysed. Demographic information, medical history, and magnetic resonance imaging features were collected. Classification of nodular fasciitis was performed based on a redefined system. Comparison between 2 groups was performed with Chi-square or Fisher exact test.For nodular fasciitis, the longest average lesion diameter was 1.87 cm (range, 0.52-5.46 cm), and 40.7% of lesions were located in the upper extremities, while 29.6% were located in the head and neck. Compared with skeletal muscle, most lesions exhibited isointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging, and 45.5% of the lesions exhibited rim enhancement, 40.9% showed obvious homogenous enhancement, while 13.6% showed no enhancement or slight enhancement. The subcutaneous type accounted for 25.9% of cases, the fascial type 25.9%, the intramuscular type 29.6%, and the unclassified type 18.5%. The "fascia tail sign" was more frequently observed in nodular fasciitis than in other soft tissue lesions (P < .001). Nodular fasciitis was slightly more likely to present with the "inverted target sign" and "solar halo sign" than other soft tissue lesions (P > .05). The "cloud sign" only appeared in nodular fasciitis (P < .05).The "fascia tail sign" and "cloud sign" could help differentiate nodular fasciitis from other soft tissue lesions. A new classification may improve understanding about nodular fasciitis.

Myxoid neoplasms of bone and soft tissue: a pattern-based approach

INTRODUCTION

The accurate diagnosis of musculoskeletal neoplasms is difficult but a pattern-based approach combined with ancillary testing has been shown to improve diagnostic accuracy. The pattern-based approach is particularly appropriate for myxoid lesions.

MATERIALS AND METHODS

The authors reviewed their personal experience of over 3 decades of diagnosing myxoid neoplasms of musculoskeletal lesions.

RESULTS

The authors found that myxoid lesions can be accurately classified based on cell type, nuclear atypia, presence of blood vessel fragments, as well as the results of immunohistochemical and molecular testing.

CONCLUSIONS

Musculoskeletal lesions with a prominence of myxoid or chondroid material in the background can be accurately diagnosed using pattern analysis and ancillary testing.

Cytomorphological features of an unusual case of a multifocal pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma in a young adult male

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma (PMHE) is a relatively newly described vascular neoplasm, characterized by distinct clinicopathological and molecular features, with no report on its cytomorphological features on smears, till date. A 17-year-old male presented with multiple nodules on his left upper limb. Radiologic imaging disclosed multiple lesions involving the soft tissues, skin, and bones of his left upper limb. Biopsy of one of the lesions on his left ring finger revealed a cellular tumor comprising plump spindle and epithelioid cells, containing moderate to abundant, eosinophilic cytoplasm; mild nuclear atypia, vesicular nuclear chromatin, discernible nucleoli, infrequent mitotic figures, and interspersed neutrophils. Immunohistochemically, tumor cells were positive for AE1/AE3, CD31, and FLI-1, while negative for CD34 and desmin. INI1/SMARCB1 was retained. MIB1/Ki67 highlighted nearly 3% tumor cells (low). Diagnosis of a PMHE was offered. A simultaneous fine needle aspiration cytology smears of the lesions in his left forearm and ipsilateral axillary region revealed spindle and some polygonal shaped cells, arranged in tight and loose clusters, as well as scattered singly, containing abundant cytoplasm with tapering cell membranes, at places; vesicular nuclear chromatin and characteristic intercellular fibrillary stromal material. The present case constitutes the first report on cytomorphological features of a PMHE, diagnosed on cytology, including its differential diagnoses, immunohistochemical features with molecular updates.

Assessing the diagnostic accuracy for pleomorphic adenoma and Warthin tumor by employing the Milan System for Reporting Salivary Gland Cytopathology: An international, multi-institutional study

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has established distinct diagnostic categories for reporting cytopathological findings, and each is associated with a defined risk of malignancy (ROM). However, the ROM is applied at the overall category level and is not specific for particular morphological entities within a category. Here, the diagnostic performance of the MSRSGC for pleomorphic adenoma (PA) and Warthin tumor (WT) is reported.

METHODS

The pathology archives of 11 institutions from 4 countries were retrospectively searched to identify all salivary gland fine-needle aspiration (FNA) biopsies with a differential or definitive diagnosis of PA or WT and all resection specimens with a diagnosis of PA or WT; only paired cases were included. All FNA diagnoses were retrospectively classified according to the MSRSGC.

RESULTS

A total of 1250 cases met the inclusion criteria, and they included 898 PA cases and 352 WT cases. The ROM in the benign neoplasm category was 3.0% and 1.3% for cases with a differential or definitive diagnosis of PA and WT, respectively. The ROM in the salivary gland neoplasm with uncertain malignant potential (SUMP) category was 2.7% and 18.8% for PA and WT, respectively (P = .0277). The diagnostic accuracy for PA and WT was 95.1% and 96.1%, respectively.

CONCLUSIONS

The diagnostic accuracy for PA and WT on FNA is high. Furthermore, these findings highlight the difference in the ROMs associated with 2 specific differential diagnoses in the SUMP category: basaloid neoplasms and oncocytoid neoplasms.

A Novel COL1A1-CAMTA1 Rearrangement in Cranial Fasciitis

Cranial fasciitis is an uncommon benign fibroblastic tumor, generally histologically identical to nodular fasciitis. It develops almost exclusively in children. Cranial fasciitis manifests clinically as a painless rapidly growing solitary nodule in the head and neck area, frequently eroding the underlying bone. Thus, this entity is often confused with aggressive lesions such as sarcomas, both clinically and radiologically. Histopathologic examination is essential to differentiate between cranial fasciitis and fibrohistiocytic or even sarcomatous lesions observed in children. In this article, we present a case of cranial fasciitis with intracranial extension in a 2-year-old boy. Although USP6 rearrangement has recently been recognized as a recurring alteration in nodular fasciitis, we present a novel COL1A1-CAMTA1 fusion in this lesion.

Cytomorphologic findings of low-grade fibromyxoid sarcoma

INTRODUCTION

Low-grade fibromyxoid sarcoma (LGFMS) is a rare fibroblastic tumor characterized by a prolonged clinical course and malignant biological behavior. Given its deceptively bland cytomorphology, a diagnosis can be quite challenging notably on fine-needle aspiration (FNA). In an attempt to shed light on some of the distinctive cytomorphologic characteristics, this study was conducted to review all cases of LGFMS in our database, correlating available clinical data, immunohistochemical findings, and molecular analysis.

MATERIALS AND METHODS

This series included 20 FNAs from 18 patients with a histologically confirmed LGFMS diagnosis from 3 large academic institutions. Detailed cytomorphologic analysis for each case was documented in conjunction with corresponding clinical characteristics and provided ancillary testing.

RESULTS

Out of 14 adequate FNA samples, 9 (64.2%) demonstrated a mixture of fibrous and myxoid pattern; the majority of cases were composed of deceptively bland tumor cells with rare nuclear pleomorphism and nuclear membrane irregularities. A MUC4 immunostain was performed on 5 specimens; all tested positive (100%). FUS rearrangement was detected in 4 out of 5 cases (80%). Follow-up information revealed 5-year recurrence in 1 case and metastatic disease in 2 cases, to the lung/pleura (8 years) and fourth rib (1 year), respectively.

CONCLUSIONS

The presence of bland spindle cells and associated with myxoid matrix material, in the appropriate clinical setting, can suggest LGFMS and direct additional confirmatory testing. A definitive diagnosis of LGFMS on FNA requires adequate sampling, familiarity with key cytomorphologic features, acquisition of diagnostic material for a cell block preparation and ancillary testing, and clinicoradiologic correlation.

Cytological Diagnosis and Misdiagnosis of Nodular Fasciitis

Background

Nodular fasciitis (NF) is a rapidly growing, self-limiting, subcutaneous nodular cytologic exuberant fibroblastic/myofibroblastic proliferation prone to cytological misdiagnosis.

Aims

This study aimed at finding out the utility of fine needle aspiration cytology (FNAC) from NF patients and to validate the diagnostic features.

Materials and Methods

The study group comprised 11 cases diagnosed as NF on cytology or subsequent histology.

Results

Out of 11 cases, 9 were cytologically diagnosed as NF. Two cases were misdiagnosed as sarcoma as proven histologically. Of the 9 cases of NF, spontaneous resolution occurred in 7 cases in 2-16 weeks; excisional biopsy was undertaken in the other 2 cases.

Conclusion

On cytology, NF reveals hypercellular, polymorphic, dispersed cell population, which is most commonly misdiagnosed as sarcoma. For this reason, FNAC has to be correlated with clinical data and followed up for the anticipated spontaneous regression.

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.

The role of fine-needle aspiration cytology in the diagnosis of soft tissue nodules: Experience in a tertiary center

INTRODUCTION

Excisional or core needle biopsy is considered the gold standard for diagnosing soft tissue lesions (STL). However, the role of fine-needle aspiration cytology (FNAC) in STL remains controversial.

MATERIALS AND METHODS

We have reviewed 234 FNAC of STL diagnosed in our institution with the aim of analyzing the reliability of FNAC in STL. Cytological diagnoses were classified into groups and correlated with histological diagnoses. We have also reviewed the literature and compared our results with those previously reported.

RESULTS

The majority of patients were male (53.4%) and mean age was 61 years. Lesions were mainly located in the head and neck region. Inadequate material was obtained in 22.6% of cases and most lesions were inflammatory lesions or benign soft tissue tumors. Carcinoma and benign soft tissue tumor were the most frequent cytological diagnoses. Biopsy was performed in 36.1% of cases, and carcinoma was detected in 33.3% of inflammatory FNACs. General and specific concordances were 65.9% and 47.1%. Diagnostic sensitivity, specificity, negative and positive predictive values were 71.4%, 100%, 85.7% and 93.8%, respectively.

CONCLUSIONS

FNAC of STL is a valuable tool for diagnosing benign epithelial cysts, carcinomas, hematolymphoid neoplasms and benign soft tissue tumors. Inflammatory smears may be associated with false-negative cases. The availability of a multidisciplinary team, clinical and imaging features, ROSE and immunohistochemical and molecular techniques is required for improving the role of FNAC of STL.

Cytopathologic characteristics of HPV-related small cell carcinoma of the oropharynx

BACKGROUND

Human papillomavirus (HPV)-related squamous cell carcinoma (SqCC) of the oropharynx is an epidemiologically and clinically distinct form of SqCC that is associated with an improved prognosis. However, HPV-related small cell carcinoma of the oropharynx is a rare and newly described variant that is associated with aggressive clinical behavior and poor outcomes. To date, fewer than 2 dozen reports of this entity exist in the literature, and there is no discussion of cytopathologic features. This article reports 6 cases and discusses the salient cytomorphologic findings, ancillary studies, and challenges when this entity is encountered.

METHODS

Anatomic pathology archives were searched to identify patients with a diagnosis of HPV-related small cell carcinoma of the oropharynx. Medical records were reviewed to document the following: age, sex, smoking status, other relevant clinical history, primary location, treatment, and clinical outcome. Both p16 and high-risk HPV in situ hybridization (ISH) studies were positive in at least 1 specimen from each patient. The pathologic diagnoses, cytomorphologic characteristics, immunocytochemical stains, and HPV ISH studies were reviewed and recorded for all available cases.

RESULTS

Six patients with 11 cytopathology specimens of HPV-related small cell carcinoma of the oropharynx were identified. The mean age was 61.3 years, and all patients died with widely metastatic disease (mean, 23 months; range, 12-48 months). Mixed small cell carcinoma and SqCC components were present in half of the cases.

CONCLUSIONS

The identification of a small cell component can be reliably performed with cytology preparations and is crucial because this (and not the HPV status) determines the prognosis.