An unusual case of adamantinoma of long bone

Abstract

Adamantinoma of the long bones is an exceedingly rare and slow-growing tumor that affects the diaphysis of long bones, particularly the tibia. Based on the pattern of the epithelial cell component and the presence or absence of the osteofibrous dysplasia-like element, several histological variants have been described, such as (i) tubular (the most frequent), (ii) basaloid, (iii) squamous, (iv) spindle variant, (v) osteofibrous dysplasia -like variant, and (vi) Ewing's sarcoma -like adamantinoma (the least frequent). The diagnosis may be challenging since this tumor may be mistakenly interpreted as carcinoma, myoepithelial tumor, osteofibrous dysplasia, and vascular tumor. We report the case of a 41-year-old male who presented with swelling over the right leg associated with pain. The X-ray showed a lytic lesion of the right-sided tibia. The diagnosis of adamantinoma was made based on the clinico-radiological, histomorphology, and immunohistochemical findings. Histologically, classic adamantinoma is a biphasic tumor characterized by epithelial and osteofibrous components in varying proportions and differentiating patterns. The diagnosis can be confirmed by immunohistochemistry for demonstrating sparse epithelial cell nests when the radiological features are strongly consistent with adamantinoma. This case is highlighted because the epithelial component can lead to a misdiagnosis, particularly when the clinico-radiological features are overlooked. Adamantinoma of long bones has the potential for local recurrence and may metastasize to the lungs, lymph nodes, or other bones. The prognosis is good if early intervention is taken.

Adamantinoma: An Updated Review

“…However, the tumor is rare in childhood (21). Adamantinoma is divided into two types: classic adamantinoma, where the mean patient's age is about 40 years, and differentiated adamantinoma, where the patients are up to 20 years old (22). In addition, it is possible the true prevalence of adamantinoma is underestimated, as in previous years, these tumors might have been confused with osteofibrous or fibrous dysplasia (23).…”

“…Osteofibrous-like adamantinoma has a better outcome than classic adamantinoma (43). Classic adamantinoma is classified into four patterns of growth namely basaloid, tubular, spindlecell and squamous (22). The basaloid pattern consists of solid masses of basaloid cells.…”