Rekhi Bharat, Dave Vinayak, Butle Ashwin, Dutt Amit
Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, Maharashtra, India; Homi Bhabha National Institute (HBNI) University, Parel, Mumbai, Maharashtra, India.
Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, Maharashtra, India.
Ann Diagn Pathol. 2023 Oct;66:152174. doi: 10.1016/j.anndiagpath.2023.152174. Epub 2023 Jun 21.
Despite its characteristic clinicopathological features, chondroblastoma may pose a diagnostic challenge, given its morphological spectrum, potential for subdiagnostic appearances in limited biopsy specimens, and its potential mimicry of other entities. Recently, a characteristic H3F3B mutation underlying most chondroblastomas was described, which led to the identification of H3.3K36M as the corresponding diagnostic immunohistochemical marker. The present study is an evaluation of immunohistochemical features of 26 chondroblastomas, including DOG1 and H3.3K36M immunostaining. H3.3K36M immunostaining was graded as 1+, 2+ and 3+ in terms of staining intensity. There were 17 males and 9 females (M:F = 1.8:1) with ages ranging from 7 to 34 years (average = 16.7, median = 16). The most common location was proximal humerus (8, 30.7 %) followed by proximal tibia (5, 19.2 %), distal femur (3, 11.5 %), proximal femur (3, 11.5 %), pelvis (2,), followed by distal tibia, calcaneum, upper sternum, scapula, and D9 vertebra, in a single case, respectively. Eighteen (69.23 %) tumors displayed all the classic histopathological features. Immunohistochemically, the tumor cells were positive for S-100 P (19/22, 86.3 %), DOG1 (focal to patchy) (21/23 91.3 %), and H3.3K36M (26/26, 100 %). H3.3K36M tested in other tumors, constituting diagnostic mimics of a chondroblastoma, such as giant cell tumor of bone, chondromyxoid fibroma, and tenosynovial giant cell tumors, showed negative staining. Six tumors, initially diagnosed as chondroblastomas were reclassified into other entities with the help of negative H3.3K36M immunostaining. The present study reinforces H3.3K36M as a highly sensitive and specific marker for diagnosing chondroblastoma, including small biopsies, and in uncommon tumor sites with variable histopathological features. DOG1 is also useful in reinforcing a diagnosis of chondroblastoma in a clinicoradiological context, especially in laboratories lacking H3.3K36M immunostain. However, its staining pattern is variable.
尽管软骨母细胞瘤具有特征性的临床病理特征，但鉴于其形态学谱、有限活检标本中可能出现的诊断不足表现以及对其他实体的潜在模仿，其诊断可能具有挑战性。最近，描述了大多数软骨母细胞瘤潜在的一种特征性H3F3B突变，这使得H3.3K36M被鉴定为相应的诊断性免疫组化标志物。本研究评估了26例软骨母细胞瘤的免疫组化特征，包括DOG1和H3.3K36M免疫染色。根据染色强度，H3.3K36M免疫染色分为1+、2+和3+。患者共17例男性和9例女性（男:女 = 1.8:1），年龄范围为7至34岁（平均 = 16.7岁，中位数 = 16岁）。最常见的部位是肱骨近端（8例，30.7%），其次是胫骨近端（5例，19.2%）、股骨远端（3例，11.5%）、股骨近端（3例，11.5%）、骨盆（2例），其余分别为胫骨远端、跟骨、胸骨上段、肩胛骨和第9胸椎，各1例。18例（69.23%）肿瘤表现出所有典型的组织病理学特征。免疫组化方面，肿瘤细胞S-100P阳性（19/22，86.3%）、DOG1阳性（局灶至斑片状）（21/23，91.3%）、H3.3K36M阳性（26/26，100%）。在其他可模仿软骨母细胞瘤诊断的肿瘤中检测H3.3K36M，如骨巨细胞瘤、软骨黏液样纤维瘤和腱鞘巨细胞瘤，结果显示为阴性染色。6例最初诊断为软骨母细胞瘤的肿瘤，在H3.3K36M免疫染色阴性的帮助下被重新分类为其他实体。本研究强化了H3.3K36M作为诊断软骨母细胞瘤的高度敏感和特异标志物的作用，包括小活检标本以及组织病理学特征多样的罕见肿瘤部位。在临床放射学背景下，DOG1也有助于软骨母细胞瘤的诊断，尤其是在缺乏H3.3K36M免疫染色的实验室。然而，其染色模式存在差异。
