METASTATIC ANGIOMATOID FIBROUS HISTIOCYTOMA PRESENTING AS RECURRENT PNEUMOTHORAX

Abstract

SESSION TITLE: Lung Cancer: Unusual Presentations SESSION TYPE: Med Student/Res Case Report PRESENTED ON: 10/21/2019 3:15 PM - 4:15 PM INTRODUCTION: Angiomatoid fibrous histiocytoma (AFH) is known as an uncommon low-grade malignant soft tissue tumor of uncertain histogenesis. It tends to occur most commonly in the subcutaneous or deep dermis of the extremities in children and young adults. The majority of the cases occur in the extremities, although lesions occurring in the head and neck region (10%) have been reported. World Health Organization (WHO) in 2002 removed AFH as a subtype of malignant sarcoma and placed it in the category of tumors of uncertain differentiation because a majority of patients (73.2%) were disease-free after local excision, while a minority (23.2%) developed recurrent disease and 8.7% developed metastatic disease within 24 months post operation . Here, we present an uncommon case of a rare tumor where metastatic disease to the lung was diagnosed after the patient had episodes of spontaneous pneumothoraxes. CASE PRESENTATION: This is a 27-year-old male with no significant history that presented with left-sided neck pain. A CT scan of the neck revealed a 4 x 4 x 5 cm neck mass and subsequently had surgical excision. Pathology showed clear margins with a spindle cell neoplasm consistent with angiomatoid fibrous histiocytoma. He then completed a course of adjuvant radiotherapy. Several months later, the patient developed right-sided pneumothorax which recurred twice, imaging revealed bilateral pulmonary nodules. He had another admission with recurrent pneumothorax and repeat imaging revealed enlargement of these nodules, the larges 2.6 x 3.8 cm in size. He underwent CT-guided biopsy of the right-sided nodule along with bilateral pleurodesis. The pathology results showed metastatic disease consistent with the pathology of his primary malignancy. DISCUSSION: AFH is a rare neoplasm with a typically benign clinical course, metastatic disease is extremely rare. A recent review of the literature found 17 cases of metastatic AFH, 7 of those cases had metastatic disease to the lung. Unfortunately, patients with distant metastases tend to have fatal outcomes and in the review, those treated with chemotherapy had no improvement in their survival. EWSR1-CREB1 gene fusion is the most common genetic abnormality described in 70% of AFH with interleukin-6 (IL-6) secretion thought to promote tumor growth. A recent case report of a patient with metastatic AFH that did not respond to chemotherapy had improvement with anti-IL-6 targeted treatment. As more research in targeted therapies are conducted there is hope that better outcomes will be found in patients with metastatic AFH CONCLUSIONS: AFHs are extremely rare, with metastatic disease being even rarer. Due to the uncommon nature of the disease, it can often lead to erroneous diagnosis of a malignant disease potentially leading to inappropriate treatment. Therefore, it is of significant relevance to increase its awareness among health care providers. Reference #1: Chen G et al. Angiomatoid fibrous histiocytoma: unusual sites and unusual morphology. Modern Pathology 2011; volume 24: 1560-1570 Reference #2: Saito K et al. Angiomatoid fibrous histiocytoma: a series of seven cases including genetically confirmed aggressive cases and a literature review. Musculoskeletal Disorders (2017) 18:31 DOI 10.1186/s12891-017-1390-y Reference #3: Maher et al. Characterization of Metastatic Angiomatoid Fibrous Histiocytoma. J Pediatri Hematol Oncol. 2015; 37:268-271 DISCLOSURES: No relevant relationships by Augusto Amaral Neto, source=Web Response No relevant relationships by Omar Ibrahim, source=Web Response No relevant relationships by Stefan Kachala, source=Web Response No relevant relationships by Vinay Mathew-Thomas, source=Web Response No relevant relationships by Carissa Monterroso, source=Web Response