Double-hit multiple myeloma with myelomatous pleural effusion: a case report

Multiple myeloma(MM) accounts for approximately 10% of all hematologic neoplasms, with double-hit multiple MM(DHMM) 10–20% of MM cases. Pleural effusion occurs in approximately 6%–14% of patients with MM. The vast majority of these cases are benign, while only about 1% involve malignant pleural effusion directly attributable to myelomatous infiltration (i.e., myelomatous pleural effusion(MPE)). However, the co-occurrence of DHMM and MPE has been extremely rarely reported, and there is currently a lack of large-scale studies to elucidate the correlation between high-risk cytogenetic abnormalities(CAs) and the development of MPE. This study aims to analyze the clinicopathological characteristics, cytogenetic alterations, therapeutic course, and prognostic outcomes of this case, with the objective of providing valuable insights for early diagnosis, personalized treatment strategies, and survival prognosis assessment in patients with similar conditions. This study reports a case of a 71-year-old Han male who was diagnosed with IgG Lambda type MM with high-risk 1q21 gene amplification and t(4;14) gene fusion, and MPE occurred two months later. Due to the patient's poor physical condition and limited economic resources, they were unable to receive specialized treatment for MM and only received symptomatic and supportive care.The patient succumbed to the disease more than two months following the onset of MPE. The overall survival (OS) was only four months and a few days. We report a rare case of DHMM complicated by MPE. Whether double‑hit cytogenetics directly increase the risk of MPE remains unknown and requires larger studies.Consequently, upon definitive diagnosis, aggressive specialized therapeutic interventions should be promptly initiated, provided the patient's overall condition permits.This type of case is relatively rare, exhibiting poor response to treatment, a high propensity for early recurrence and disease progression, and a short OS. Currently, there is no standardized treatment protocol, and a comprehensive systematic review through large-scale clinical studies is lacking. Future investigations should specifically examine the association between high-risk cytogenetic profiles and MPE development, with the goal of identifying molecular drivers that may inform risk stratification and novel targeted therapies.