Neoadjuvant radiation therapy for the management of myoepithelial carcinoma of the upper extremity

Abstract

Myoepithelial tumors of the soft tissue are a rare tumor displaying myoepithelial elements and lacking obvious ductal differentiation. The rarity of these precludes any evidence-based consensus regarding optimal management. Nevertheless, the current approach to these lesions begins with amputation or complete excision. The efficacy of neoadjuvant or adjuvant radiation therapy or chemotherapy has not been established. Here, we present the first report to the authors’ knowledge of neoadjuvant radiation therapy for the treatment of this rare soft tissue neoplasm and review the management and outcomes of published cases of myoepithelial carcinoma. A patient with a soft tissue myoepithelial carcinoma that declined both amputation and chemotherapy was treated with neoadjuvant radiation therapy and wide surgical excision followed by a brachytherapy boost to the resected tumor bed. Neoadjuvant radiation therapy resulted in an excellent response with extensive treatment-related changes consisting predominantly of fibrosis, hyalinization and hemorrhage and only 10% residual viable myoepithelial carcinoma present in the surgical specimen.

Impending Doom: A Rare Case of Metastatic Myoepithelial Carcinoma

“…The resected specimen revealed only 10% viable tumor cells indicating excellent tumor response. This further reinforces the benefit of radiotherapy as a treatment modality [16]. Platinum-based chemotherapy has been utilized in recurrent or metastatic disease following resection with limited benefits [6].…”

“…It is advised that myoepithelial neoplasms are best examined with a tumor panel that includes all antibodies to broad-spectrum keratins, high-molecular-weight keratins, and myofilaments [6]. About 95% of tumors express reactivity to keratin (CKAE 1/3), S100, EMA, PAN-K, CAM 5.2, pan-cytokeratin, calponin, SMA, muscle-specific actin (MSA), smooth muscle myosin, P63 protein, glial fibrillary acidic protein (GFAP), CD10, desmin, and p63 [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In our case, the tumor was immunoreactive to SOX-10, CKAE 1/3, CAM 5.2, BCL-2, vimentin, and S100 confirming the diagnosis of myoepithelial carcinoma.…”

“…Given the rarity of this malignancy, the clinical course and treatment modalities remain undefined. Multiple treatment modalities have been described in case reports, ranging from complete surgical resection with clear margins to chemotherapy and/or neoadjuvant /adjuvant radiotherapy [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. There are limited reports of deep soft tissue myoepithelial carcinoma with concurrent metastasis and rapid mortality [10][11][12][13].…”

Soft tissue myoepithelial carcinoma—a case report with molecular and electron microscopic analysis

“…In a systematic review of myoepithelial tumors in soft tissue by Rastrelli et al, 10 studies were found, with a total of 233 patients, and only three of these reported malignancy (10). Correspondingly, a review by Kabarriti et al found only 58 published cases of the malignant version, that is myoepithelial carcinoma, in soft tissue (2). Recently, a retrospective study by Chamberlain et al described 24 cases in their institution over a period of 23 years.…”

“…Primary myoepithelial tumors in soft tissue have been increasingly described over the past decade, but are challenging to diagnose due to their rarity as well as morphologic and immunohistochemical heterogeneity. A recent review found 58 published cases of primary myoepithelial carcinoma in soft tissue, and a later published retrospective singlecenter study found 24 cases over the last 23 years (2,3). Thus, there are fewer than 100 well-documented cases of myoepithelial carcinoma till date.…”