Chondroblastoma of foot bones; a clinicopathological study of 29 cases confirming the diagnostic utility of H3K36M and H3G34W antibodies at an uncommon site

• Published in: Annals of diagnostic pathology 2023-08, Vol.65, p.152135-152135, Article 152135
• Main Authors: Tariq, Muhammad Usman, Din, Nasir Ud, Qureshi, Madiha Bilal, Park, Yong-Koo
• Format: Article
• Language: English
• Subjects: Antibodies; Bone and Bones - pathology; Bone Neoplasms - diagnosis; Bone Neoplasms - pathology; Chondroblastoma; Chondroblastoma - diagnosis; Chondroblastoma - pathology; Female; Foot; Foot Bones - pathology; H3G34W antibody; H3K36M antibody; Humans; Immunohistochemistry; Male
• ISSN: 1092-9134; 1532-8198
• DOI: 10.1016/j.anndiagpath.2023.152135

Chondroblastoma (CB) is a benign cartilaginous bone neoplasm which commonly occurs in long bones of adolescents. CB can uncommonly involve foot. Its mimics include both benign and malignant lesions. H3K36M immunohistochemical (IHC) stain is a helpful tool for establishing the diagnosis of CB in such challenging situations. In addition, H3G34W IHC stain helps to rule out giant cell tumor which is the closest differential of CB. Our objective was to describe the clinicopathological features and frequencies of H3K36M, H3G34W and SATB2 IHC stains in CB of foot. We reviewed H&E slides and blocks of 29 cases diagnosed as “chondroblastoma” of foot at our institutions. Patient's age ranged from 6 to 69 (mean: 23.3 and median: 23) years. Males were almost 5 times more commonly affected than females. Talus and calcaneum were involved in 13 (44.8 %) cases each. Microscopically, tumors were composed of polygonal mononuclear cells and multinucleated giant cells and chondroid matrix. Other histological features included aneurysmal bone cyst-like (ABC-like) change (44.8 %), osteoid matrix (31 %), chicken-wire calcification (20.7 %), and necrosis (10.3 %). H3K36M was expressed in 100 % and SATB2 in 91.7 % cases. H3G34W was negative in all cases, where performed. One out of 11 patients with follow up information developed local recurrence after 48 months. CB in foot occur at an elder age and show more frequent ABC-like changes as compared to long bones. Males are affected ~5:1 as compared to 2:1 in long bones. H3K36M are H3G34W are extremely useful diagnostic markers for CB, especially elderly (aged or higher) patients and we report the largest series of foot CB cases confirmed by immunohistochemistry. The diagnostic utility of H3K36M and H3G34W immunohistochemical markers and clinicopathological features in 29 cases of Chondroblastoma of foot: H3K36M is expressed in all 29/29 cases and H3G34W is negative in 29/29 cases. Chondroblastoma of foot present at older age and show more frequent aneurysmal bone cyst (ABC)-like changes. [Display omitted] •Chondroblastoma of foot is rare and few large series have been published.•Chondroblastoma of foot occurs at older age compared to those occurring in long bones.•Chondroblastoma of foot show frequent aneurysmal bone cyst like change.•H3K36M is a useful marker for confirmation of diagnosis especially in small biopsies.