Adamantinoma of the distal femur diagnosed 5 years after initial surgery: a case report

Abstract

Background: Adamantinoma arising in the femur is extremely rare. We report a case of an adamantinoma occurring in the right medial femoral condyle that was diagnosed 5 years after the primary surgery.

Case presentation: A 74-year-old Asian woman first complained of right knee pain without any cause. Radiographs demonstrated a 4×4.5 cm osteolytic lesion in her medial femoral condyle. Magnetic resonance imaging revealed a lesion which showed low signal on both T1 and T2-weighted image, and enhanced signal with gadolinium contrast administration. She underwent a wide resection of the lesion and was reconstructed with a tumor endoprosthesis. On histological examination, the tumor showed clusters of spindle-shaped and squamoid epithelial cells among the fibrous stroma. Adamantinoma was considered, however, the diagnosis was inconclusive due to the unusual localization and her age. Moreover, it was difficult to exclude metastatic carcinoma. Five years later, she was diagnosed with an abnormal shadow occupying the upper lobe of her right lung in a routine physical examination. She subsequently underwent a resection of the lung mass which histologically showed proliferation of spindle-shaped and squamoid epithelial cells. The histological similarity of the lung tumor and the femoral tumor led to the diagnosis of adamantinoma arising in her right medial femoral condyle with metastasis to the upper lobe of her right lung.

Conclusion: In this case report, we report the clinical, radiographic, and histological features of an adamantinoma arising in the distal femur with a review of the literature.

Keywords: Adamantinoma; Distal femur; Medial femoral condyle; Metastatic adamantinoma.

Fig. 1

Plain radiographs of the tumor in the distal femur. Anteroposterior and lateral radiographs show a 4×4.5 cm osteolytic lesion in the right medial femoral condyle

Fig. 2

Magnetic resonance imaging of the tumor in the distal femur. On magnetic resonance imaging, the tumor was depicted as a low signal lesion on T1-weighted image (a), low to intermediate intensity on T2-weighted image (b), and highly enhanced with gadolinium contrast (c). There was no apparent destruction of the cortex and no soft tissue mass was present

Fig. 3

Histopathology of the femoral lesion. The tumor shows clusters of epithelial cells that were oval or spindle-shaped with squamous differentiation, and surrounded with fibrous stroma. Tumor cell nuclei are relatively uniform, did not show pronounced atypia, and have a low rate of mitosis (hematoxylin and eosin)

Fig. 4

Intraoperative finding. Wide resection of the tumor was performed and was reconstructed with a tumor endoprosthesis (a). Anteroposterior (b) and lateral (c) radiograph after operation

Fig. 5

Computed tomography imaging of the lung. Five years after initial surgery, the patient took a routine physical examination including chest computed tomography which revealed an abnormal shadow occupying her right upper lung (arrow)

Fig. 6

Histopathology of the upper lung lesion. The tumor shows proliferation of spindle-shaped and squamoid epithelial cells with mild nuclear atypia, surrounded with fibrous stroma, which is strikingly similar to the histopathological findings of the femoral lesion (a). The epithelial cells spread around the alveolar wall without destruction of the alveolar structure (b). Immunostaining of thyroid transcription factor-1 demonstrates preserved epithelial cells of alveolar wall. The tumor cells are negative for thyroid transcription factor-1 (c)

Fig. 7

Positron emission tomography-computed tomography findings at the latest follow-up. Fluorodeoxyglucose uptake suggested a recurrent tumor in the right upper lobe of the lung (a) and a metastasis to the spinal vertebrae (b)