Masato Sugawara

Isocitrate dehydrogenase 2 mutation is a frequent event in osteosarcoma detected by a multi-specific monoclonal antibody MsMab-1.

Somatic mutations of isocitrate dehydrogenase (IDH) 1 and IDH2 occur in gliomas, acute myeloid leukemia, and cartilaginous tumors. Somatic mosaic IDH1/2 mutations are also reported in Ollier disease and Maffucci syndrome, which are characterized by multiple central cartilaginous tumors. Although IDH1/2 mutation analysis against osteosarcoma has been performed in several studies, no IDH1/2 mutation has been reported. Herein, we newly report the IDH2‐R172S mutation in three of 12 (25%) osteosarcoma patients, which was detected by direct DNA sequencing. No monoclonal antibody (mAb) has been reported against IDH2‐R172S mutation. However, we demonstrate that the IDH2‐R172S peptide was recognized by our established multi‐specific anti‐mutated IDH1/2 mAb, MsMab‐1, in enzyme‐linked immunosorbent assay. Western blot analysis revealed that MsMab‐1 reacts with PA tag combined recombinant proteins of IDH2‐R172S. Furthermore, MsMab‐1 stained IDH2‐R172S‐expressing osteosarcoma tissues in immunohistochemistry. The MsMab‐1 stained nine of 32 (28.1%) osteosarcomas in a tissue microarray. This report is the first describing IDH2 mutations in osteosarcoma, which can be detected by MsMab‐1 mAb. Taken together, these results show that MsMab‐1 can be anticipated for use in immunohistochemical determination of IDH1/2 mutation‐bearing osteosarcoma.

Isocitrate dehydrogenase mutation is frequently observed in giant cell tumor of bone

Giant cell tumors of bone (GCTB) are benign and locally destructive tumors that include osteoclast‐type multinuclear giant cells. No available treatment is definitively effective in curing GCTB, especially in surgically unresectable cases. Isocitrate dehydrogenase (IDH) mutations have been reported not only in gliomas and acute myeloid leukemias, but also in cartilaginous tumors and osteosarcomas. However, IDH mutations in GCTB have not been investigated. The IDH mutations are remarkably specific to arginine 132 (R132) in IDH1 and arginine 172 (R172) or arginine 140 (R140) in IDH2; IDH1/2 mutations are known to convert α‐ketoglutarate to oncometabolite R(‐)‐2‐hydroxyglutarate. We recently reported that the most frequent IDH mutation in osteosarcomas is IDH2‐R172S, which was detected by MsMab‐1, a multispecific anti‐IDH1/2 mAb. Herein, we newly report the IDH mutations in GCTB, which were stained by MsMab‐1 in immunohistochemistry. DNA direct sequencing and subcloning identified IDH mutations of GCTB as IDH2‐R172S (16 of 20; 80%). This is the first report to describe IDH mutations in GCTB, and MsMab‐1 can be anticipated for use in immunohistochemical determination of IDH1/2 mutation‐bearing GCTB.

Pyloric gland metaplasia/differentiation in multiple organ systems in a patient with Peutz–Jegher's syndrome

Peutz‐Jeghers syndrome (PJS) involves multiple organ systems and the development of hamartomatous, metaplastic, or neoplastic lesions of different cell lineages. Among them, glandular lesions are the most common, but their properties are obscure. We report here a 53‐year‐old woman with PJS who developed multiple hamartomatous polyps in the jejunum and mucinous glandular lesions in multiple organ systems: glandular metaplasia in the urinary bladder; lobular endocervical glandular hyperplasia in the uterine cervix; mucinous metaplasia in the right fallopian tube; mucinous adenoma in the left ovary. Histological and immunohistochemical analyses disclosed that all of the intestinal and extra‐intestinal lesions were associated with pyloric gland metaplasia/differentiation across the organ systems. In the general population, the organs described above rarely or infrequently show pyloric gland phenotype, to say nothing of trans‐organ involvement. It is strongly suggested that commitment to pyloric gland metaplasia/differentiation is closely associated with PJS.

RUNX2 expression in developing human bones and various bone tumors

The heterozygous germline mutation of runt‐related protein 2 (RUNX2) causes cleidocranial dysplasia. To clarify the involvement of RUNX2 in human osteogenesis, fetal bones and various bone tumors were immunohistochemically examined. During both membranous and endochondral ossification in the fetus (n= 8), RUNX2 was expressed not only in osteoblastic cells but also in surrounding mesenchymal cells and early stage chondrocytes. Such an expression pattern was recapitulated in bone tumors: RUNX2 was unequivocally expressed in osteosarcoma (n= 20) and fibrous dysplasia (n= 10), regardless of the site of occurrence, cell morphology or amount of neoplastic osteoid. RUNX2 expression was limited to less differentiated cells in chondrogenic tumors (n= 20). We further analyzed whether RUNX2 expression was regulated by bone morphogenetic protein‐2 (BMP‐2), which is critical for osteoblastic differentiation. With real‐time polymerase chain reaction, the RUNX2 mRNA level was correlated with BMP‐2 mRNA level, and both levels were significantly higher in three osteosarcoma cell lines than in three chondrosarcoma cell lines. With treatment of recombinant BMP‐2, the RUNX2 mRNA level was significantly altered in these cell lines. RUNX2 expression is constitutive in developing and neoplastic human osteogenesis, and is most likely to be regulated by BMP‐2.

Histologic Examination of Leeds-Keio Artificial Ligament Implanted on the Surface of a Tumor Endoprosthesis

The Leeds-Keio (L-K) artificial ligament is made of polyester fibers with an open-weave mesh structure. It has been used clinically for knee ligament reconstruction as a scaffold, allowing tissue ingrowth and new ligament formation. We have used the L-K ligament in bone tumor surgery for reattaching remaining muscles to the target zone of a tumor endoprosthesis. We histologically examined the L-K ligament obtained from 2 patients during revision surgery 39 months after the primary surgery. There were dense fibrous tissues between muscles and the L-K ligament. Collagen fibers proliferated in the space between the polyester fibers, and a slight inflammatory reaction was apparent. We concluded that the L-K ligament had a high potential for inducing biological tissue regeneration even on the metal surface.

Clonal expansion of multiple pulmonary leiomyomatous hamartoma: 12-year follow-up

To the Editor: In 1999 we reported on a 31-year-old woman with multiple pulmonary leiomyomatous hamartoma (MPLH). MPLH is a peculiar lesion of the lung, the individual lesions of which are composed of a mixture of smooth muscle and glandular elements. There is no apparent topographical relationship between the lesion and the bronchial trees or vascular structures, although a previous ultrastructural study suggests a possible relation to the contractile system of the lung acini. MPLH is not associated with specific pathological conditions of the lung, including interstitial pneumonia or lymphangioleiomyomatosis, whereas there has been controversy regarding whether MPLH is equivalent to benign metastasizing leiomyoma. The clinical course of MPLH also remains unclear, because there have been a few reports of long-term follow up of patients with MPLH. We have followed the present patient for 12 years. The patient went on to develop numerous nodules in both lungs, and a total 242 nodules (128 from the right lung and 114 from the left lung) were enucleated, although each nodule was indolent and the patient was asymptomatic. The diameters of the nodules were between 2 and 18 mm, and the pathological diagnosis for these nodules was pulmonary leiomyomatous hamartoma. The latest nodule in the left upper lobe, however, had rapid growth: it was 13 mm in diameter in September 2007, but had grown to 25 mm by September 2008. Macroscopically, this nodule, as well as the previous nodules, had a well-demarcated border and a gray–white cut surface without necrosis. The histological features, however, differed between the large nodule and the previous nodules. The previous nodules were composed of spindle-shaped cells arranged in interlacing fascicles, among which a few glands were scattered. The spindleshaped cells had eosinophilic cytoplasms and elongated nuclei without atypia. No mitotic figures were observed (Fig. 1a). In contrast, the majority of the large nodule consisted of spindle-shaped cells, which proliferated in fascicles with high cellularity. No glandular elements were scattered among them (Fig. 1b). Although these spindle-shaped cells, as well as those in the previous nodules, had eosinophilic cytoplasms, those from the large nodule showed nuclear atypia with a high mitotic activity of up to 7 mitotic figures per 10 high-power fields (HPF; Fig. 1c). Neither atypical mitoses nor necrosis was observed. In the periphery of the large nodule, there was a small area exhibiting features similar to those of the previous nodules (Fig. 1d). Immunohistochemically, the majority of spindle-shaped cells, irrespective of nodule size, were positive for a-smooth muscle actin, and some of them were also positive for desmin and h-caldesmon (Fig. 2a). Immunoreactivity with Ki-67 was different among nodules: the spindle-shaped cells of the previous nodules were rarely positive for Ki-67, whereas those of the large nodule had an increased Ki-67 index of up to 10% (Fig. 2b). No expression of estrogen or progesterone receptor was detected in any nodules. Melanosomeassociated antigen was not expressed either. A 12 year follow-up of this patient shed light on the nature of MPLH. First, the clinical course strongly indicated that MPLH is distinct from benign metastasizing uterine leiomyoma (BML). For a long time, there has been controversy regarding whether MPLH is equivalent to BML. BML is an ill-defined clinicopathological condition, which features “metastatic” histologically benign smooth muscle tumor deposits in the lung, lymph node, or abdomen, which appear to be derived from a benign uterine leiomyoma. Almost all cases of BML occur in women who have a history of uterine leiomyoma. In the present case, the patient had no history of myomectomy. Periodic clinical examinations over 12 years had not led to the detection of any uterine lesions, in spite of the detection of numerous pulmonary nodules. It is extremely unlikely that a missed uterine leiomyoma was the source of these pulmonary nodules. This is also supported by the present data on clonality: the small nodule was found to have a polyclonal pattern on clonality analysis using the human androgen receptor (HUMARA) gene as a target (Fig. 2c). If the nodules were derived from a uterine leiomyoma, they ought to be monoclonal. It has been reported that the clonality of BML nodules obtained from a patient with a history of uterine leiomyoma was monoclonal. All of these facts indicate that MPLH is distinct from BML. The occurrence of MPLH in men and children is also best explained by this conclusion. Second, long-term observation showed that the hamartomatous nodules have the potential to transform into true neoplasm. Among 242 nodules resected, one nodule had atypical biological and histological features. It grew rapidly and showed monomorphic proliferation of atypical smooth muscle cells with increased cellularity. The nodule exhibited a small area of leiomyomatous hamartoma in the periphery, as observed in the other nodules. On clonality analysis, the cellular area was found to no longer show a polyclonal pattern but rather a monoclonal pattern (Fig. 2c). All Pathology International 2009; 59: 828–830 doi:10.1111/j.1440-1827.2009.02453.x

Malignant Peripheral Nerve Sheath Tumor of the Femur: A Rare Diagnosis Supported by Complete Immunohistochemical Loss of H3K27me3

The histological diagnosis of malignant peripheral nerve sheath tumor (MPNST) is challenging because of the wide morphological spectrum and suboptimal performance of conventional immunohistochemical markers. MPNST arising primarily in the bone is exceptional, and its definitive diagnosis, particularly out of the neurofibromatosis type 1 (NF1) context, is even more problematic. Recurrent inactivation of EED or SUZ12 in a majority of MPNSTs results in a complete loss of trimethylated histone H3 at lysine 27 (H3K27me3) immunoreactivity, making it a highly specific biomarker of MPNSTs. In this article, we report a case of sporadic MPNST of the proximal femur that showed complete loss of H3K27me3. The patient was treated with limb-sparing surgery and postoperative radiotherapy. He developed multiple lung and bone metastases 4 months after surgery. Our case confirms the utility of H3K27me3 immunohistochemistry to yield a definitive diagnosis of sporadic MPNST in a rare primary site.

Treatment of bone and soft-tissue sarcoma patients in Japan: The distribution of patients and medical specialties by cancer topography and treatment modality.

e22544Background: Sarcoma clinical guidelines often emphasize the evaluation of patients by an expert multidisciplinary team, and thus in many countries, care is centralized to treatment centers. However, there are no standard guidelines for referrals of sarcoma patients in Japan, and the overall picture of where and by whom they are treated has never been systematically investigated. Methods: We used hospital-based cancer registry and health claims data of sarcoma patients diagnosed in Japan in 2012 and 2013. We analyzed the distribution of patients across hospitals and the extent of centralization of care across treatment modality and cancer topography. Results: We identified 1032 bone and 7257 soft-tissue sarcoma (STS) patients who were newly diagnosed in 2012 and 2013. Bone sarcomas occurred in the limbs in 55% of the patients, with 73% treated by orthopedic surgeons. Care was weakly centralized to 9 high-volume hospitals ( > 10 new cases per year) and 120 hospitals with 1-9 new cases. Care was greatl...