SESSION TITLE: Cancer Case Report Posters II
SESSION TYPE: Affiliate Case Report Poster
PRESENTED ON: Tuesday, October 29, 2013 at 01:30 PM - 02:30 PM
INTRODUCTION: Lung cancer is known to metastasize to distant organs, however, metastasis to the skeletal muscles or soft tissue is very rare. Patients developing distant metastases are in advanced stage of disease and are almost always symptomatic. Literature review has shown few cases of lung cancer presenting primarily with a soft tissue mass. Here, we report a case of non-small cell lung cancer (NSCLC) diagnosed primarily from biopsy of a soft tissues mass. The patient had no pulmonary or systemic symptoms.
CASE PRESENTATION: A 54-year-old male smoker with no other significant past medical history presented with swelling and a 2cm x 2cm, firm, nontender, nonpulsatile soft tissue mass above the left knee. The mass started approximately 3 weeks prior as a small nodule, which has gradually increased. He denied any trauma, fever, chills or pain with ambulation. Review of systems was negative for cough, hemoptysis, weight loss, shortness of breath and fatigue. Physical exam was otherwise normal, including no palpable lymphadenopathy, organomegaly, clubbing or cyanosis. Respiratory exam was within normal limits. Immunohistochemical analysis of sonogram-guided subcutaneous tissue biopsy was in favor of large cell carcinoma of lung origin (figure 1b). Subsequently, chest radiograph and chest CT revealed a 7 x 5.2 x 6 cm right upper lobe mass with necrotic mediastinal and hilar lymphadenopathy (figure 2). Adenocarcinoma of the lung was confirmed on lung biopsy (figure 1a).
DISCUSSION: Soft tissue metastasis is an uncommon presenting manifestation of an internal malignancy. Lung cancer is a common cause of cutaneous metastasis; however pulmonary symptoms are usually present in such cases. The exact mechanism for skin and soft tissue involvement in metastatic lung cancer remains unclear. Ideally soft tissue metastasis remains resistant to hematogenous spread due to factors such as variable blood flow, muscular contractile actions, local pH and accumulation of metabolites like lactic acid. Thereby, lung cancer spread to skeletal muscle, in absence of other pulmonary or systemic symptoms is highly unlikely. Once NSCLC has metastasized to soft tissue, the median survival rates range from around 5 to 19 months.
CONCLUSIONS: In patients presenting with skin and soft tissue mass, internal organ malignancy should be suspected in appropriate clinical setting, once other common causes of soft tissue mass are ruled out. In patients with internal organ malignancy that have soft tissue metastasis, lung cancer remains a common cause.
Reference #1: Cutaneous metastasis: a clinical, pathological, and immunohistochemical appraisal. J Cutan Pathol. 2004 Jul;31(6):419-30.
Reference #2: Metastatic carcinoma to skeletal muscle. A report of 15 patients. Clin Orthop Relat Res. 1998 Oct;(355):272-81.
Reference #3: Possible reasons for the high resistance of muscle to cancer Med Hypotheses. 1980 Feb;6(2):133-7.
DISCLOSURE: The following authors have nothing to disclose: Abhay Vakil, Ahmed Abubaker, Hineshkumar Upadhyay, Viral Patel, Kelly Cervellione, Artur Shalanov
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