Brown tumors, an exceptional bone complication of severe primary (PHP) or renal (secondary) hyperparathyroidism (RHP), are caused by long-standing, elevated parathormone (PTH)-induced osteoclast activation causing multinucleated giant cell conglomerates with hemosiderin deposits in addition to the local production of cytokines and growth factors. We aim to present an adult case series including two females displaying this complication as part of a multidisciplinary complex panel in high PTH-related ailments. The approach was different since they had distinct medical backgrounds and posed a wide area of challenges amid real-life settings, namely, a 38-year-old lady with PHP and long-term uncontrolled hypercalcemia (with a history of pregnancy-associated PHP, the removal of a cystic jaw tumor, as well as a family and personal positive diagnosis of polycystic kidney disease, probably a PHP-jaw tumor syndrome), as well as, a 26-year-old woman with congenital single kidney and chronic renal disease-associated RHP who was poorly controlled under dialysis and developed severe anemia and episodes of metabolic acidosis (including one presentation that required emergency hemodialysis and was complicated with convulsive seizures, followed by resuscitated respiratory arrest). Both subjects displayed a severe picture of PHP/RHP with PTH levels of >1000 pg/mL and >2000 pg/mL and elevated serum bone turnover markers. Additionally, they had multiple brown tumors at the level of the ribs and pelvis (asymptomatically) and the spine, skull, and pelvis (complicated with a spontaneous cervical fracture). As an endocrine approach, the control of the underlying parathyroid disease was provided via surgery in PHP (for the postparathyroidectomy hungry bone syndrome) via medical intervention (with vitamin D analogs) in RHP. Additionally, in this case, since the diagnosis was not clear, a multidisciplinary decision to perform a biopsy was taken (which proved inconclusive), and the resection of the skull tumor to confirm the histological traits. This series highlights the importance of addressing the entire multidisciplinary panel of co-morbidities for a better outcome in patients with PHP/RHP-related brown tumors. However, in the instance of real-life medicine, poor compliance and reduced adherence to recommendations might impair the overall health status. Thus, sometimes, a direct approach at the level of cystic lesion is taken into consideration; this stands for a narrow frame of decision, and it is a matter of personalized decision. As seen here, brown tumors represent the hidden face of PHP/RHP, primarily the complex and severe forms, and awareness is essential even in the modern era.
