Osseous metaplasia in a kidney allograft

A very rare case of bone metaplasia of renal cyst: A case report

INTRODUCTION

Renal Osseous Metaplasia (OM) is a rare condition in which mature bone forms within the renal parenchyma, typically as focal cortical lesions. Although it is usually considered a spontaneous and less pathologically significant lesion, it has been observed in damaged renal allografts and other urinary tract sites. The case we present involves a native kidney with a simple renal cyst, where histopathological examination post-tumor enucleation revealed OM, emphasizing its noteworthy presence in clinical settings.

CASE PRESENTATION

A 37-year-old female with a history of cesarean delivery and recent emergency surgery presented with abdominal and left flank pain. Initial ultrasound revealed a 4.2 cm anechoic cyst in the lower pole of the left kidney, which was confirmed by abdominal computed tomography (CT-scan as a well-defined fluid density cyst with a thick calcified wall. Surgical enucleoresection identified a Stoney hard mass with a unilocular cyst, histopathologically diagnosed as a simple renal cyst with metaplastic bone and hematopoietic elements. The patient had an uneventful postoperative course and remained well during the follow-up.

DISCUSSION

Osseous metaplasia (OM) involves extraskeletal bone formation and is associated with factors such as chronic ischemia and inflammation. While rare in renal pathology, it occurs in native kidneys, damaged renal allografts, and the urinary tract, posing radiological challenges in differentiating it from calcification. Accurate diagnosis requires histopathological examination because of the difficulties in distinguishing OM from calcification on imaging studies.

CONCLUSION

This case revealed Osseous Metaplasia in a simple cyst of the native kidney, urging vigilance in the diagnosis. While generally benign, its occurrence in damaged renal areas emphasizes its clinical significance, prompting further research. Heightened awareness and thorough examination are crucial for accurate diagnosis and patient management.

In vivo diagnosis of intraocular osseous metaplasia in neovascular age-related macular degeneration

A 75-year-old man presented with deterioration of right eye vision for 6 months. He had no relevant medical history. Fundus examination revealed subretinal fluid, fibrosis, and subretinal hemorrhages. Ocular coherence tomography of the right macula illustrated an underlying subretinal lesion with internal lamellae, resembling trabecular bone elsewhere in the body. Bruch's membrane was clearly intact beneath the lesion, indicating an extrachoroidal location. The lesion appeared highly reflective on B-scan ultrasonography, consistent with ossification. Although initially misdiagnosed as choroidal osteoma, this lesion represents in-vivo intraocular osseous metaplasia at the site of neovascular age-related macular degeneration. The authors believe that similar lesions may have been misdiagnosed as “atypical” osteoma caused by failure to identify their extrachoroidal location.

Ectopic bone formation and extramedullary hematopoiesis in the thyroid gland: report of a case and literature review

This purpose of this article is to document ectopic bone formation (EBF) and extramedullary hematopoiesis (EMH) in thyroidectomy specimens. We present a case of multinodular goiter with EMH and EBF, as well as a literature review of studies published in the English language on EMH and/or bone formation in the thyroid gland, accessed through PubMed and Google Scholar databases. Thirteen published cases of EMH and/or EBF in the thyroid gland were evaluated, and a case of multinodular goiter with histopathologically proven EMH and EBF in a 54-year-old woman is herein presented. In the reviewed literature, 12 patients were women, and 1 was a man (age range, 28-82 years; median, 56.46 +/- 18 years). EMH was histopathologically detected in 8 patients, EMH and EBF were detected in 4 patients, and only bone formation was detected in 1 patient. Although a solitary nodule was detected in 7 patients, multinodular goiter was detected in 6 patients. Fine needle aspiration cytology was used in the preoperative period to arrive at a diagnosis in 6 of the 13 patients, but it was not possible to obtain proper biopsy material in the remaining patients. Although no previously known hematologic disease was detected in 11 patients, 2 were known to have myelofibrosis in the preoperative period. When EMH is pathologically detected in the thyroid, the question of whether there is an underlying hematologic disease in the patient must be investigated. In addition, it must be kept in mind during fine needle aspiration cytology and frozen section examinations that EMH maybe among the differential diagnoses for anaplastic thyroid cancers.