Case Presentation: A 58-year-old woman presented with abdominal pain, nausea, and oral intolerance. Her vitals were stable on admission, but physical exam revealed a distended abdomen with tenderness to palpation in the left lower quadrant and an absence of bowel sounds. Her laboratory results were remarkable only for a hemoglobin of 8.1, which appeared chronic. Abdominal x-ray revealed distended bowel loops, with follow up CT demonstrating enteroenteric intussusception of the left lower quadrant adjacent to an intraluminal soft tissue mass as the lead point for a suggested small bowel obstruction. At this time, the differential diagnosis included a new primary malignancy, metastasis from a secondary malignancy, or a submucosal lesion such as a gastrointestinal stromal tumor. Supportive care was begun with abdominal decompression via nasogastric tube and general surgery was consulted. The patient was subsequently taken to the operating room for exploratory laparoscopy; this revealed an intraluminal mass that was resected. Histopathologic analysis revealed a high-grade plasma cell neoplasm, concerning for extramedullary multiple myeloma (MM). After a consult to medical oncology, PET-CT revealed diffuse plasmacytomas in the thoracic spine, brain dura, and retroperitoneum. Cytogenetic abnormalities were subsequently identified, which revealed p53 mutations and CCND/IGH translocations, confirming the diagnosis of a high-risk subtype of MM.
Discussion: Extramedullary multiple myeloma (EMM) is characterized by the presence of plasma cells outside of the bone marrow and is considered a rare and aggressive subtype of MM. Hospitalists are often familiar with classical MM with end-organ manifestations of anemia, renal impairment, hypercalcemia, and bone lesions. However, EMM is much less commonly encountered but affects a much broader spectrum of organ involvement than classical MM. This subset of MM is commonly associated with poorer prognosis, diagnostic and monitoring challenges, and limited response to standard MM treatment regimens. For hospitalists, recognizing EMM as a potential diagnosis requires a broad differential and a high degree of suspicion, particularly in patients with a history of malignancy or unexplained anemia. Given that traditional manifestations of MM were absent in this patient, prompt involvement of subspecialists led to appropriate management. Advanced imaging modalities such as PET-CT can be pivotal in identifying extramedullary lesions and guiding treatment. The workup for this patient initially focused on more common etiologies of small bowel obstruction, such as gastrointestinal malignancy or metastatic disease. However, the eventual identification of EMM highlights the need for hospitalists to be aware of this rare subtype of MM, which may present with symptoms overlapping with other acute abdominal conditions.
Conclusions: Hospitalists should maintain a broad differential diagnosis when patients present with acute abdominal pain. Awareness of uncommon manifestations of common diseases, in this case EMM, can lead to timely diagnoses and definitive management. Given that they are often among the first healthcare providers to encounter a patient, swift identification and triage to the appropriate specialist also leads to timely intervention and better outcomes. By maintaining a broad differential and being vigilant for unusual presentations, hospitalists can play a critical role in the timely diagnosis and management of aggressive diseases such as EMM.
