Proximal-type epithelioid sarcoma: a new case report and literature review

Proximal-type epithelioid sarcoma is a rare soft tissue neoplasm which arises from the more proximal part of body and occurs more often in young people; the definite diagnosis depends mainly on the pathological examination; early detection and complete excision remain the foundation of treatment. Due to its aggressive behavior, high capacity of recurrence and the great ability to metastasize, a careful clinical long-term monitoring is required. We report a new case of a 20 years old girl, presented with proximal-type epithelioid sarcoma in her right scapular region, confirmed by pathological examination and removed surgically without recurrence or metastasis at eighteen months of follow-up.


Introduction
Proximal-type epithelioid sarcoma (PES) is a rare high grade softtissue sarcoma (less than 1 of all soft tissue sarcomas), typically presenting as a subcutaneous or deep dermal mass, with slow growing and high potential for distant metastasis in adolescents and young adults [1]. These tumors arise in proximal locations (trunk, axilla, genital area…), have a much worse prognosis if delayed diagnosis and treatment. Owing to its rarity, aggressive behavior, high capacity of recurrence and the difficulty of its clinical and histopathological diagnosis, we report a new case of a 20 years old girl, presented with proximal-type epithelioid sarcoma in her right scapular region removed and treated successfully.

Patient and observation
A 20 years old girl presented with a red and farm nodule since 2 years in her right scapular region; a first simple excision was performed and was in favor of a benign lesion (fibrous histiocytoma). The lesion recurred clinically six months later as two farms painless nodules and a solid plaque measuring 3.5cm in diameter ( Figure 1

Discussion
Epithelioid sarcoma was first described by Enzinger in 1970 [2]; usually arises in the distal extremities in adolescents and young adults with male prevalence; the proximal-type variant, first described in 1997 as an aggressive form of sarcoma with a great ability to metastasize and high capacity of recurrence, usually arises more proximally [3]. Proximal-type epithelioid sarcomas (PES), occur 94% in the chest wall, inguinal region, thigh and perineum, Its size at presentation varies from 0.5 to 19 cm [4], and growth duration ranges from 6 months to 5 years [5]. This uncommon neoplasm is a pitfall in clinical diagnosis and it is likely to be confused with benign lesions resulting in delayed diagnosis and treatment [6]. PES can be diagnosed only through histological examination [7] showing a pleomorphic epithelioid and oval spindled malignant cells with numerous mitoses exhibiting slight nuclear atypia, vesicular nuclei and small nucleoli, transition between the two cell types is gradual and intercellular collagen deposition usually marked [4,8]; it can be distinguished from poorly differentiated carcinoma, rhabdomyosarcoma, synovial sarcoma, malignant mesothelioma, and melanoma using immunohistochemistry [9].
Immunohistochemically, PES is characteristically immunoreactive for vimentin and epithelial markers: low and high molecular weight cytokeratins, keratin 8, keratin 19 and/or EMA. Half of the cases are also positive for CD34 [10]. Several publications about misdiagnosis and prognosis of PES have been raised currently. Fisher et al [11] emphasize the importance of using immunohistochemicals markers to the diagnostic of specific soft tissue tumors specially coexpression of CD34 and cytokeratins in PES cells. Mannan et al [12] report a case of PES in a 47-year-old man, to emphasize the importance of diagnosing of this challenging tumor and the role of immunohistochemistry in establishing the diagnosis. Wide local excision with adequate margins (at least 2 cm) is recommended [13]; adjuvant radiotherapy is advocated in high-grade tumors or inadequate surgical margins [14], and also due to high incidence of local recurrence and distant metastasis [10], However it is controversial and it did not show statistically significant reduction in mortality [15]. The role of chemotherapy in the adjuvant setting appears marginally effective at best in the treatment of metastatic disease [16]. The prognosis for PES remains worse; despite negative surgical margins, tendency to recur is highly possible and distant metastasis eventually occurs in up to 60% of cases [14] Ulbright et al. [17] reported in their review of the literature that all patients with local recurrence ultimately died from distant metastasis. Our patient had initially a 2-years history of a progressively growing nodule over the right scapular region, which could be considered as a proximal type variant. As the lesion was

Competing interests
Authors declare no competing interest.

Authors' contributions
The authors have read the final version of this manuscript. Figure 1: The two farms painless nodules and a solid plaque on the right scapular region