Summary

Brown tumors are osteoclastic, benign lesions characterized by fibrotic stroma, intense vascularization and multinucleated giant cells. They are the terminal expression of the bone remodelling process occurring in advanced hyperparathyroidism. Nowadays, due to earlier diagnosis, primary hyperparathyroidism keeps few of the classical manifestations and brown tumors are definitely unexpected. Thus, it may happen that they are misdiagnosed as primary or metastatic bone cancer. Besides bone imaging, endocrine evaluation including measurement of serum parathyroid hormone and calcium (Ca) levels supports the pathologist to address the diagnosis. Herein, a case of multiple large brown tumors misdiagnosed as a non-treatable osteosarcoma is described, with special regards to diagnostic work-up. After selective parathyroidectomy, treatment with denosumab was initiated and a regular follow-up was established. The central role of multidisciplinary approach involving pathologist, endocrinologist and oncologist in the diagnostic and therapeutic work-up is reported. In our opinion, the discussion of this case would be functional especially for clinicians and pathologists not used to the differential diagnosis in uncommon bone disorders.

Learning points:

• Brown tumors develop during the remodelling process of bone in advanced and long-lasting primary or secondary hyperparathyroidism.

• Although rare, they should be considered during the challenging diagnostic work-up of giant cell lesions.

• Coexistence of high parathyroid hormone levels and hypercalcemia in primary hyperparathyroidism is crucial for the diagnosis.

• A detailed imaging study includes bone X-ray, bone scintiscan and total body CT; to rule out bone malignancy, evaluation of bone lesion biopsy should include immunostaining for neoplastic markers as H3G34W and Ki67 index.

• If primary hyperparathyroidism is confirmed, selective parathyroidectomy is the first-line treatment.

• In advanced bone disease, treatment with denosumab should be considered, ensuring a strict control of Ca levels.

Summary

Primary amenorrhea could be caused by disorders of four parts: disorders of the outflow tract, disorders of the ovary, disorders of the anterior pituitary, and disorders of hypothalamus. Delay in diagnosis and hormone substitution therapy causes secondary osteoporosis. Herein, we report a case of a 23-year-old phenotypical female who presented with primary amenorrhea from 46, XX gonadal dysgenesis but had been misdiagnosed as Mayer–Rokitansky–Kuster–Hauser (MRKH) syndrome or Mullerian agenesis. The coexistence of gonadal dysgenesis and MRKH was suspected after laboratory and imaging investigations. However, the vanishing uterus reappeared after 18 months of hormone replacement therapy. Therefore, hormone profiles and karyotype should be thoroughly investigated to distinguish MRKH syndrome from other disorders of sex development (DSD). Double diagnosis of DSD is extremely rare and periodic evaluation should be reassessed. This case highlights the presence of estrogen deficiency state, the uterus may remain invisible until adequate exposure to exogenous estrogen.

Learning points:

• An early diagnosis of disorders of sex development (DSD) is extremely important in order to promptly begin treatment, provide emotional support to the patient and reduce the risks of associated complications.

• Hormone profiles and karyotype should be investigated in all cases of the presumptive diagnosis of Mayer–Rokitansky–Kuster–Hauser (MRKH) syndrome or Mullerian agenesis.

• The association between 46, XX gonadal dysgenesis and Mullerian agenesis has been occasionally reported as a co-incidental event; however, reassessment of the presence of uterus should be done again after administration of exogenous estrogen replacement for at least 6–12 months.

• A multidisciplinary approach is necessary for patients presenting with DSD to ensure appropriate treatments and follow-up across the lifespan of individuals with DSD.