Non-small cell lung cancer with concomitant intramuscular myxoma of the right psoas mimicking intramuscular metastasis: A case report and literature review

Abstract

Abstract. Intramuscular myxoma (IMM) as a rare soft-tissue tumor arising from the muscles is completely benign. When IMM accompanies malignance, it may be misdiagnosed as muscle metastasis, and for this extremely rare concurrence, the subsequent treatment would vary accordingly. The current study presents, to the best of our knowledge, the first case of non-small cell lung cancer (NSCLC) concomitant with IMM mimicking skeletal muscle metastasis. A 64-year-old female was hospitalized with a history of chest discomfort and right lumbar pain that had persisted for four months. The computed tomography scan showed a lesion in the left upper lobe of the lung and the right psoas, respectively. Serum biomarkers for NSCLC were abnormal. A presumptive clinical diagnosis was compatible with left NSCLC and right psoas muscle metastasis (cT2aN3M1b, stage Ⅳ). Stage Ⅳ lung cancer would receive palliative treatment. However, the final diagnosis of synchronous left lung squamous cell carcinoma (cT2aN3M0, stage ⅢB) and IMM in the right psoas was confirmed by biopsy. The patient therefore underwent definitive chemoradiotherapy for lung carcinoma, and conservative treatment, including analgesics, for IMM. The diagnosis process for a malignant neoplasm concomitant with IMM is not straightforward due to a lack of clinical experience, and it significantly affects the tumor staging and subsequent treatment strategy. The present case suggests that IMM should be included in the differential diagnosis when an abnormal intramuscular lesion concomitant with malignancy is identified. The value of histopathological diagnosis prior to definitive treatment also requires highlighting.

Muscle involvement by widely metastatic squamous cell carcinoma of the lung

“…Other factors that have been suggested include the immunological cause i.e. cellular and humoral immunity, and the strong hypersensitivity reaction within the muscles [8] .…”

Squamous cell carcinoma lung with skeletal muscle involvement: A 8-year study of a Tertiary Care Hospital in Kashmir

“…The most important hypotheses are mechanical (muscle contraction, high tissue pressure,[ 15 ] and extremely variable blood flow),[ 16 ] metabolic (pH, lactic acid production[ 17 ] and toxic-free radical oxygen)[ 15 ] or immunologic (cellular and humoral immunity and hypersensitivity reaction). [ 18 ] None of them in isolation can explain the full mechanism, but a combination of them could.…”

Rare forearm intramuscular myxoma: a case report

“…Intramuscular myxoma (IMM) are benign soft tissue that account for 0.1 to 0.13 per 100,000 populations (1). Various theories have been described regarding the mechanism of IMM occurrence.…”