Cytological and histological detection of amyloid deposits in bone marrow of patients affected by multiple myeloma

We recently published a study aiming to verify the frequency of amyloid deposits in the bone marrow of patients with multiple myeloma (MM) who did not present any signs or symptoms of systemic amyloidosis, applying the Congo red technique on bone marrow smears obtained by aspiration from the posterior iliac spine. The results suggested that nearly 40% of patients affected by MM may have amyloid deposits in their bone marrow. Subsequently, this finding has not been confirmed by another study performed with histological specimens of bone marrow in a similar clinical setting. To explain this discrepancy, we performed a comparative study on the bone marrows of 36 patients affected by MM, evaluated by both cytological and histological techniques. The results of this study confirm the high frequency of amyloid deposits in the bone marrow of patients affected by MM when the analysis is made on cytological smears, and indicate that the presence of amyloid on marrow smears is confirmed by core biopsies simultaneously performed in only 25% of cases. Should further studies confirm our findings, cytological assessment could be considered a sensitive technique to detect bone marrow amyloid deposits.