Hematological Malignancy in a Hypophysectomised Acromegalic Patient Under 4-Year Therapy with Somatostatin Analogues: From a Rib Lump Underlying Bone Plasmatocytoma Features to Multiple Myeloma

Acromegaly is associated with a higher risk of certain malignancies, but not hematological neoplasia, although multiple myeloma (MM) was found in very limited cases. We aim to present such a case, adding a particular presentation with co-occurrence of a plasmocytoma. A 52-year-old male with acromegaly confirmed at 46 (MRI: pituitary macroadenoma of 12 × 11 × 10 mm) underwent hypophysectomy followed by 3 years of octreotide LAR then lanreotide depot. After another 6 months, he experienced a rapidly growing, painful lump in the right lateral thoracic area confirmed by CT as a 9-cm osteolytic lesion at the third rib. Core biopsy revealed plasmocytoma of the bone and medullary biopsy confirmed MM. Plasmacytoma was managed with 10 radiotherapy sessions, with favorable outcome and mass resorption; MM was managed with a VRD regimen, followed by autologous hematopoietic stem-cell transplantation. Six months after sFLC normalization and plasmacytoma resorption, complete remission was reported. In the meantime, lanreotide was continued, with complete acromegaly control. To conclude, what started as a rather typical scenario for an otherwise rare condition, as is acromegaly in the general population (but not so rare for endocrinologists), turned into an unexpected and more severe outcome. Noting this exceptional association, we pinpoint that further research is needed for understanding the dual acromegaly-MM relationship.