Bortezomib, cyclophosphamide, and dexamethasone: highly effective for rapid reversal of myeloma-associated hyperammonemic encephalopathy

Hyperammonemic Encephalopathy: A Rare Presentation of Relapsed Multiple Myeloma

Hyperammonemia is a rare cause of encephalopathy in multiple myeloma in the absence of hepatic involvement. This is the only reported case of a 74-year-old man who presented with multiple myeloma and achieved complete remission but developed hyperammonemia afterward. He was aggressively treated with a combination of chemotherapy and immunotherapy, with a resolution of his encephalopathy; however, within one month, he relapsed with encephalopathy. He ultimately decided to pursue comfort-care measures. The authors conclude that hyperammonemia in multiple myeloma is a rare but important differential in patients with encephalopathy of unknown causes. Aggressive treatment is of the utmost importance due to the high mortality associated with the condition.

Non-producer multiple myeloma presenting with acute hyperammonemic encephalopathy: case report

BACKGROUND

Hyperammonemic encephalopathy (HE) is a rare and life-threatening complication of multiple myeloma, with underlying mechanisms that are not fully understood. In contrast to previously reported cases, most of which have been associated with IgG or IgA isotypes, we describe a patient with HE as the presenting symptom of non-producer multiple myeloma (NPMM).

CASE PRESENTATION

A 60-year-old man developed lethargy that progressed into coma. He was found to have an elevated ammonia level, despite normal hepatic function. He was diagnosed with HE secondary to NPMM, demonstrating 80% plasma cells without light chain expression in the bone marrow and absence of a monoclonal protein in the serum or urine, including by matrix-assisted laser desorption ionization time-of-flight mass-spectrometry (MASS-FIX). Myeloma-directed therapy with daratumumab, bortezomib, cyclophosphamide and dexamethasone successfully reversed his HE. At clinical relapse, he received salvage chemotherapy followed by venetoclax therapy, leading to a short period of neurological recovery.

CONCLUSIONS

This case demonstrates that HE can occur in a patient with NPMM and challenges the mechanism suggested by limited prior studies; i.e., that excess ammonia in multiple myeloma arises from degradation of M-proteins. We postulate that the neoplastic plasma cells in NPMM have amplified amino acid metabolism, despite lacking detectable intracellular or secreted immunoglobulins.

A Case of Fatal Hyperammonaemic Encephalopathy in a Patient with End-Stage Multiple Myeloma

n.

The Role of the Gut Microbiome in Pathogenesis, Biology, and Treatment of Plasma Cell Dyscrasias

In response to emerging discoveries, questions are mounting as to what factors are responsible for the progression of plasma cell dyscrasias and what determines responsiveness to treatment in individual patients. Recent findings have shown close interaction between the gut microbiota and multiple myeloma cells. For instance, that malignant cells shape the composition of the gut microbiota. We discuss the role of the gut microbiota in (i) the development and progression of plasma cell dyscrasias, and (ii) the response to treatment of multiple myeloma and highlight faecal microbiota transplantation as a procedure that could modify the risk of progression or sensitize refractory malignancy to immunotherapy.

Multiple Myeloma-Induced Hyperammonemic Encephalopathy

Multiple myeloma (MM) typically presents with hypercalcemia, renal insufficiency, anemia, and bone lesions. Elevated ammonia level manifesting as altered mental status is a rare complication in MM. We report an interesting case of hyperammonemic encephalopathy in a 73-year-old male with advanced relapsing kappa-light chain MM.