Cytomorphological study of soft tissue neoplasms: role of fluorescent immunocytochemistry in diagnosis

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.

Core Needle Biopsy versus Fine Needle Aspiration Cytology in Bone and Soft Tissue Tumors

Fine needle aspiration cytology (FNAC) for diagnosis of musculoskeletal tumors is well discussed and debated. The current evidence restricts its application in recurrent and metastatic lesions, with core needle biopsy as the acceptable technique/gold standard for the primary diagnosis of these challenging tumors. However, there are several studies showing reasonable sensitivity and specificity in primary diagnosis of bone and soft tissue tumors, especially in differentiating benign from malignant tumors. There is an acceptable limitation in the exact subtyping of soft tissue tumors, based on cytology smear examination, in the absence of ancillary techniques. Nonetheless, cytology constitutes an optimal material for triaging cases for ancillary techniques, such as immunocytochemistry, immunohistochemistry, molecular cytogenetics, and molecular diagnosis, in the form of smears and cell block preparations. This review focuses on the strengths and limitations of cytology versus core needle biopsy in the diagnosis of bone and soft tissue tumors, with the current evidence in the form of published studies, including the authors' experience.

Low-grade myxofibrosarcoma presenting at the site of prior high-grade disease

Myxofibrosarcoma is one of the most common soft tissue sarcomas occurring in older adults. It can arise de novo or can be radiation induced, and the term myxofibrosarcoma was originally devised to encompass a spectrum of myxoid tumors with characteristics similar to malignant fibrous histiocytoma (MFH). Confusion exists, however, regarding the distinction between microscopic grade and characteristics of myxofibrosarcoma and MFH. Correct classification is vital to prognosis, as the degree of myxoid change is inversely related to the incidence of metastasis. We present a case of a 76-year-old man with a history of high-grade MFH of the left lower extremity, status post excision and radiation therapy, who presented 2 years later with a regional metastatic recurrence of high-grade MFH to the left groin as well as new nodules adjacent to and within his prior excision and radiation site. These new nodules were determined to represent low-grade myxofibrosarcoma. These new low-grade lesions either represent a low-grade recurrence of high-grade sarcoma or a new, radiation-induced soft tissue sarcoma occurring at the same site. Radiotherapy, however, is an unlikely cause; specific postradiation sarcoma criteria have not been fulfilled. This article discusses both the nosology and histopathological spectrum of these important soft tissue sarcomas, their aggressive and recurrent nature and their association with radiation therapy.

Fine needle aspiration cytology of malignant endovascular papillary angioendothelioma

Here we described a rare case of malignant endovascular papillary angioendothelioma (Dabska tumor) in an adult female. On fine needle aspiration, the smear showed many small clusters of tumor cells with rosettoid arrangement along with papillary fragments with fibrovascular core and hobnail like arrangement of the cells. Histopathological examination revealed a vascular tumor in the form of papillary projection into the vascular lumina, lined by atypical endothelial cells.

Primary solitary fibrous tumor (SFT) in the retroperitoneum

BACKGROUND

Solitary fibrous tumor (SFT) is an infrequent but distinct neoplasm, which generally arises from submesothelial connective tissue in the pleura. SFT is rarely recognized in extrathoracic sites, and histologically identical conditions have also been reported in the retroperitoneum, although their pathophysiology has not been extensively investigated.

METHODS

We present four cases of primary SFT in the retroperitoneum, and review 37 similar cases in the previous literature.

RESULTS

About 40% of patients were asymptomatic, and 19.2% and 15.4% presented with an abdominal mass and urinary symptoms, respectively. The tumor size ranged between 2 and 26 (mean 9.1) cm. Sixty-three percent of tumors showed nonspecific development with haphazard distribution of bland short spindle or polygonal cells with or without collagenous bundles and stromal hyalinization. In 22.0%, hemangiopericytomatous appearance was seen. About 15% of cases showed histologically malignant characteristics. The tumor cells were immunoreactive for vimentin in all cases, CD34 in 91% and Bcl-2 in 86%. All tumors were excised, and in 85.4% of cases, tumors did not recur postoperatively for 6 to 48 months. No significant difference was found between the recurrence rate of histologically benign and malignant cases. Cases positive for both CD34 and Bcl-2 had no recurrence.

CONCLUSIONS

The identification of SFT in the retroperitoneum is of importance because histopathological indicators of malignancy are not necessarily associated with clinical malignant potential in many cases of retroperitoneal SFT. Retroperitoneal SFT showing typical pathological features with expression of CD34 and Bcl-2 is associated with a favorable outcome following excision.

Scope of FNAC in the diagnosis of soft tissue tumors--a study from a tertiary cancer referral center in India

BACKGROUND

Fine needle aspiration cytology (FNAC) forms one of the first diagnostic tools in the evaluation of tumors. Its role in diagnosing soft tissue tumors (STT) has been fairly documented, as well as debated. Present study was aimed at evaluating its scope in diagnosing 127 cases of soft tissue tumors.

METHODS

Conventional Pap and MGG staining was available in all the cases. Immunocytochemistry (ICC) was performed in 15 cases. Histopathological details were available in 115 cases.

RESULTS

50% cases were referred for a primary diagnosis, while 26.8% & 22.8% cases were evaluated for recurrent and metastatic lesions, respectively. Extremities were the commonest sites. On FNAC, 101 cases (79.5%) were labeled as malignant, whereas 10 cases (7.9%) were labeled as benign. The remaining 16 cases (11%) were not categorized and were labeled as 'unsure/not specified'. Histopathological confirmation in 115 cases, gave a diagnostic accuracy of 98%, with a positive predictive value of 98% in malignant cases and a negative predictive value of 100% in benign cases. Two cases were false positive. Among the various cytological categories, 60 cases (47.2%) were of spindle cell type, followed by 32 (25.2%) of round cell type and 14 cases (11%) of lipomatous type. Other 12 cases (9.4%) were of pleomorphic type; 7 (5.5%) cases of epithelioid type and remaining 2 cases were of myxoid type. All the round cell, pleomorphic and myxoid type of tumors were sarcomas, whereas 73.3% cases of spindle cell type were labeled as 'malignant'. Exact cytological sub typing was offered in 58 cases, with rhabdomyosarcoma (RMS) as the most frequently sub typed tumor. The two false positive malignant cases were of fibromatosis and a pigmented schwannoma, on biopsy. Out of 28 metastatic lesions, lymph nodes were the commonest site for metastasis, with epithelioid tumors that formed highest percentage of metastatic cases.

CONCLUSION

FNAC is fairly specific and sensitive in STT diagnoses for primary, recurrent and metastatic lesions. The cytological types, especially round cell and pleomorphic sarcomas, can be quickly identified. Clinicopathological correlation with ICC as an adjunct, are valuable in exact sub typing.