Chondroblastoma of the distal femoral metaphysis: A case report with emphasis on imaging findings and differential diagnosis

Periosteal chondroblastoma of the femoral neck: two cases and a review of the literature

Chondroblastoma is a rare benign cartilaginous tumor mostly confined to the epiphyses and apophyses. Cases outside the epiphyseal region are exceedingly rare. Extramedullary chondroblastomas are exceptional; to our knowledge, only two cases qualified as "periosteal chondroblastoma" have been described in the literature. We report two cases of metaphyseal periosteal chondroblastoma both located on the inferior surface of the femoral neck. Both cases were paucicellular with an unusual dense sclerotic reaction. The diagnosis of chondroblastoma was supported by the expression of histone 3.3, K36M mutant in tumor cells.

A rare case of chondroblastoma involving the distal phalanx of the ring finger

Chondroblastoma, a rare benign bone tumor, is typically found in the epiphysis of long bones, with hand involvement being particularly uncommon. We present a case of an 11-year-old female with chondroblastoma involving the fourth distal phalanx of the hand. Imaging revealed a lytic, expansile lesion with sclerotic margins and no soft tissue component. A preoperative differential diagnosis included intraosseous glomus tumor, epidermal inclusion cyst, enchondroma, and chronic infection. The patient underwent open surgical biopsy and curettage for both diagnostic and treatment purpose. The final histopathologic diagnosis was chondroblastoma.

Images of giant cell tumor and chondroblastoma around the knee: retrospective analysis of 99 cases

Background

It is difficult to differentiate giant cell tumors of the bone (GCTB) from chondroblastoma around the knee based on imaging findings. This study analyzed the imaging features of these 2 diseases for better differentiation.

Methods

This retrospective cross-sectional cohort study reviewed data of patients with pathologically confirmed GCTB (n=81; age 15-75 years; median age 33 years) and chondroblastoma (n=18; age 12-34 years; median age 14 years). In all, 18 imaging signs were analyzed.

Results

Patients with chondroblastoma were relatively younger than those with GCTB. On imaging, lesion length was significantly (P<0.00001) smaller in chondroblastoma [range, 15.80-78.30 mm; mean ± standard deviation (SD) 34.15±18.24 mm; 95% confidence interval (CI): 24.05-44.25 mm] than in GCTB [range, 30.10-117.50 mm; mean ± SD 59.73±15.28 mm; 95% CI: 56.24-63.22 mm]. Significantly more (P<0.05) chondroblastoma lesions had calcification (76.5% vs. 1.3%), lobulation (77.8% vs. 32.1%), and swelling range >15 mm (84.6% vs. 41.1%) than did GCTB lesions, whereas significantly more (P<0.05) GCTB lesions were greater than half the host bone diameter (74.1% vs. 16.7%) and had a lesion long axis that was consistent with that of the host bone (98.8% vs. 27.8%). There were no significant differences (P>0.05) between the 2 tumors in the remaining 11 imaging signs.

Conclusions

A narrow zone of transition, intratumor calcification, lobulation, tumor transverse diameter greater than the bone diameter, maximum lesion length, consistency between the tumor and bone long axes, and edema range around the lesion >15 mm are parameters that can be used to differentiate GCTB from chondroblastoma around the knee.

Metaphyseal chondroblastoma in a pediatric patient

Chondroblastoma is a rare, benign neoplasm usually located in the epiphyses and apophyses of the long bones in the immature skeleton. Radiologically, these tumors have a classic appearance of a lytic lesion with chondroid matrix surrounded by a thin sclerotic rim. Here, we describe the case of a 5-year-old male who presented with a chondroblastoma unusually located exclusively in the metaphyseal region, which led to an elusive diagnosis. The presence of tumors outlying the traditional location or epidemiological spectrum, along with the potential for histopathological misdiagnosis, can pose a diagnostic and therapeutic challenge for the treating team.

H3.3 K36M Mutation as a Clinical Diagnosis Method of Suspected Chondroblastoma Cases

Objective

Whether H3.3 K36M mutation (H3K36M) could be an approach if the diagnosis of chondroblastoma (CB) patients was indistinct and it was suspected to be unclear clinically.

Methods

We reviewed and compared our clinical experiences of CB cases and some suspected cases, which were not diagnosed distinctly, between 2013 to 2019. A total of 15 male and four female cases included in this study were seperated into two groups, CB group and suspected case (SC) group. The CB group included 13 men and 3 women, with an age range from 9 to 54 (mean age, 22 years old). The SC group included two men and one woman, with the age range from 13 to 25 (mean age, 19 years old). In both groups the patients had been followed‐up until December 2019 and none of the patients had prior treatment history. We evaluated the clinical complaints, radiological features, and clinical‐histological features of the cases and performed an immunohistochemical (IHC) study to detect whether the H3K36M expression of cases was different, consistent with a gene‐mutation analysis.

Results

In both groups, the radiologic features of both groups appeared as round low‐density shadow with a clear edge, pathologic features showed diffuse proliferation of neoplastic cells with multinuclear giant cells. The radiological tumor size of CB group and SC group showed little difference, which was about 29.0*21.6 mm. Clinical‐immunohistochemical features of both groups showed chondroid matrix inside with naïve tumor cells, multinucleated giant cells, and ground substance cells. Most of them showed chondro‐related antibody positive (12 cases) but some of them showed S‐100 negative (four cases). The clear difference of both groups was the result of H3K36M IHC study and gene analysis. In our cases, the CB group showed diffuse H3K36M positive and the SC group showed negative. The gene mutation analysis revealed that H3K36M‐positive CB patients had K36M mutation, which were not found in the SC group. Sanger sequencing showed an A > T substitution at codon 36 of histone H3F3B. No other types of histone H3 mutation was detected in the CB group. Particularly, one of the suspected cases showed a G34W mutation was confirmed to be a giant cell tumor of bone (GCTB).

Conclusions

Our study showed H3K36M immunohistochemistry and gene mutation analysis were specific clinical diagnostic tools to distinguish suspected CB from other giant cell‐rich or cartilage matrix‐diffuse bone tumors. The clinical‐radiological and histomorphological features of patients gave suggestions on whether the H3K36M IHC and gene analysis should be required.

Anatomical Reconstruction of the Acromion Using an Autologous Iliac Crest Graft for Treatment of Recurrent Chondroblastoma: A Case Report

CASE

A 38-year-old man presented with recurrent chondroblastoma of the acromion after primary curettage and bone grafting. The patient underwent revision surgery with resection of the acromion and reconstruction using an autologous iliac crest graft. He had regained normal shoulder function without recurrence at a follow-up of 17 months.

CONCLUSIONS

This case demonstrates a rare location of chondroblastoma and successful anatomical and functional reconstruction. The described surgical procedure could be considered for large tumorous lesions of the acromion, for which curettage would be insufficient, and to preserve and reconstruct a functionally intact shoulder girdle.

Chondroblastoma of the Distal Femur in an Adolescent

An 11-year-old female was referred to physical therapy due to a 3-month history of right medial knee pain. The patient's medical diagnosis was Osgood-Schlatter disease, based on radiographs obtained at the initial pediatrician consultation. An MRI scan was obtained 2 weeks after starting physical therapy and revealed a bony lesion near the medial condyle of the right femur and damage to medial joint structures. Pathology after open biopsy and curettage of the lesion revealed a chondroblastoma. J Orthop Sports Phys Ther 2020;50(5):275. doi:10.2519/jospt.2020.9021.