Soft tissue masses: distribution of entities and rate of malignancy in small lesions

Abstract

Background Small soft tissue masses are often falsely assumed to be benign and resected with failure to achieve tumor-free margins. Therefore, this study retrospectively investigated the distribution of histopathologic diagnosis to be encountered in small soft tissue tumors (≤ 5 cm) in a large series of a tertiary referral center. Methods Patients with a soft tissue mass (STM) with a maximum diameter of 5 cm presenting at our institution over a period of 10 years, who had undergone preoperative Magnetic resonance imaging and consequent biopsy or/and surgical resection, were included in this study. A final histopathological diagnosis was available in all cases. The maximum tumor diameter was determined on MR images by one radiologist. Moreover, tumor localization (head/neck, trunk, upper extremity, lower extremity, hand, foot) and depth (superficial / deep to fascia) were assessed. Results In total, histopathologic results and MR images of 1753 patients were reviewed. Eight hundred seventy patients (49.63%) showed a STM ≤ 5 cm and were therefore included in this study (46.79 +/− 18.08 years, 464 women). Mean maximum diameter of the assessed STMs was 2.88 cm. Of 870 analyzed lesions ≤ 5 cm, 170 (19.54%) were classified as superficial and 700 (80.46%) as deep. The malignancy rate of all lesions ≤ 5 cm was at 22.41% (superficial: 23.53% / deep: 22.14%). The malignancy rate dropped to 16.49% (20.79% / 15.32%) when assessing lesions ≤ 3 cm (p = 0.007) and to 15.0% (18.18% / 13.79%) when assessing lesions ≤ 2 cm (p = 0.006). Overall, lipoma was the most common benign lesion of superficial STMs (29.41%) and tenosynovial giant cell tumor was the most common benign lesion of deep STMs (23.29%). Undifferentiated pleomorphic sarcoma was the most common malignant diagnosis among both, superficial (5.29%) and deep (3.57%) STMs. Conclusions The rate of malignancy decreased significantly with tumor size in both, superficial and deep STMs. The distribution of entities was different between superficial and deep STMs, yet there was no significant difference found in the malignancy rate.

Small (≤5 cm) soft tissue tumors of the extremity and superficial trunk: MRI features and demographic characteristics associated with malignancy

“…Gassert et al recently investigated small soft tissue masses with a diameter <5 cm in a large patient series from a tertiary referral center and confirmed that a considerable proportion of small tumors were malignant (22.4%) (9). However, despite their importance, MRI features and demographic characteristics related to small malignant soft tissue tumors are not well established.…”

“…The biologic potential of the tumors was dichotomized into benign and malignant according to the 5th edition of the World Health Organization (WHO) classification of soft tissue tumors (10). In the analysis of intermediate tumors, locally aggressive tumors that show local infiltration and destruction but do not metastasize were categorized as benign, whereas rarely metastasizing tumors that are often locally aggressive and have the potential to metastasize were categorized as malignant (9,11).…”

“…Considering that a substantial proportion of small soft tissue tumors of ≤5 cm in diameter are malignant (5%–22%) (1,2,9), further identification of the MRI features and demographic characteristics associated with these tumors would aid in their differentiation from small benign soft tissue tumors. Therefore, the aim of the present study was to investigate the MRI features and demographic characteristics of small malignant soft tissue tumors, and to identify independent predictors that allow differentiation of small benign and malignant soft tissue tumors.…”

Biopsy Ratio of Suspected to Confirmed Sarcoma Diagnosis

“…In addition, RMST depends on a multitude of other parameters. Such discrepancy in establishing the sarcoma diagnosis, however, evidences an unmet need in the work-up of sarcoma patients [ 9 ]. It may be helpful to agree on a common definition as to how to analyze biopsies to allow the comparison among multidisciplinary teams (MDTs).…”

“…In another study made in the Rhone-Alpes region in France (Lurkin et al 2010) [ 8 ], to evaluate the concordance between initial diagnosis and central pathology review for sarcoma cases, out of 366 patients diagnosed with sarcoma over a period of 1 year, 199 (54%) had full concordance between primary diagnosis (first pathologist) and second opinion (expert center pathologist), 97 (27%) had partial concordance (identical diagnosis of conjunctive tumor, but different grade or subtype), and 70 (19%) had complete discordance (different histological type or invalidation of the diagnosis of sarcoma). Another study (Gassert, F.G et al) [ 9 ] analyzed retrospectively the histopathologic findings of 1753 patients presenting with a soft tissue lesion ≤5 cm. They found that 22.4% of these lesions were malignant.…”