Ryohei Katoh

High prevalence of the MYD88 mutation in testicular lymphoma: Immunohistochemical and genetic analyses

The activating mutation of MYD88 has been identified in diffuse large B‐cell lymphoma (DLBCL). We investigated the mutational status and both the gene amplification and protein expression of MYD88 in 23 cases of testicular DLBCL. To detect the MYD88 mutations, we employed the allele‐specific PCR and Sanger sequencing. MYD88 gene amplification and protein expression were analyzed by quantitative PCR and by immunohistochemistry, respectively. There were 17 cases of primary testicular DLBCL: 94% (16/17) exhibited a non‐Germinal center B‐cell (non‐GCB) subtype, 82% (14/17) showed the MYD88u2005L265P, and 65% (11/17) had intense expression of MYD88. When compared with normal lymph nodes, the MYD88 is significantly amplified in primary testicular DLBCL. However, the amplification status showed no correlation with its mutational status or protein expression. Moreover, neither the MYD88 mutational status nor the expression pattern affected overall survival. Six cases were secondary testicular DLBCL with an 83% (5/6) and an 80% (4/5) incidence of the non‐GCB subtype and of the MYD88u2005L265P, respectively. In conclusion, we demonstrated a high prevalence of the non‐GCB subtype and the common MYD88u2005L265P in both primary and secondary testicular DLBCL. Our data suggest that the MYD88 mutation is a fairly consistent genetic feature in testicular DLBCL.

Spindle cell oncocytoma of adenohypophysis: Report of a case and immunohistochemical review of literature

We present a case of spindle cell oncocytoma (SCO) of the adenohypophysis in a 70-year-old Vietnamese male. The patient was admitted to Cho Ray Hospital after suffering from headache and visual disturbance for 6 months. Clinicians detected a 60×55×45 mm(3) mass located in the suprasellar-sellar region. Histopathologically, the resected tumor was composed of spindle cells with oncocytic appearance. Immunohistochemical examination revealed expression of anti-mitochondria antibody (AMA), vimentin, thyroid transcription factor 1 (TTF-1), epithelial membrane antigen (EMA) and galectin-3. These histologic and immunohistochemical findings are suggestive of SCO.

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma: Case report and literature review

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TL-LGNPPA) is an extremely rare neoplasm characterized by morphological analogy to papillary thyroid carcinoma and abnormal expression of thyroid transcription factor-1 (TTF-1). Here we report a novel case of TL-LGNPPA with literature review. The patient was a 43-year-old woman complaining of nasal obstruction. Laryngoscopic study and computed tomography identified a pedunculated mass located on the posterior edge of the left nasal septum. Histologically, the tumor consisted of papillary growth of cuboidal or columnar epithelium. Tubular architecture and a spindle cell component were also observed focally. Some tumor cells exhibited intra-nuclear cytoplasmic inclusions. Immunohistochemically, the neoplastic cells were positive for pancytokeratin (AE1/AE3), CK7, CK19, TTF-1, vimentin and HBME1, but negative for thyroglobulin, Pax8 and CK5/6. Ki67-labeling index reached 5% in the most concentrated spot. Despite the morphological and immunohistochemical similarity to papillary thyroid carcinoma, no BRAF V600E mutation was detected by mutation-specific immunohistochemistry. The patient had neither local recurrence nor distant metastasis 19 months after removal of the tumor.

Immunohistochemical detection of NRASQ61R protein in follicular-patterned thyroid tumors

The NRAS(A182G) mutation, which results in the NRAS(Q61R) protein, is a major driver mutation in follicular-patterned thyroid neoplasms. Although new immunohistochemistry (IHC) for NRAS(Q61R) is now available, its sensitivity, specificity, and diagnostic utility for thyroid tumors are not yet established. We performed IHC for NRAS(Q61R) and direct sequencing for NRAS codon 61 in 4 thyroid cancer-derived cell lines and 98 follicular-patterned thyroid tumors that included 22 follicular thyroid adenomas (FTAs), 35 follicular thyroid carcinomas (FTCs), and 41 cases of nodular hyperplasia (NH). In the tumors with NRAS(Q61R), the expression of BRAF(V600E) was further evaluated immunohistochemically. Two cell lines with NRAS(A182G) showed selective immunoreactivity for NRAS(Q61R). In tumor tissues, NRAS(Q61R) IHC was positive in 18% (4/22), 29% (10/35), and 2% (1/41) of FTAs, FTCs, and NH samples, respectively. The frequencies of the NRAS(Q61R) in FTAs and FTCs were significantly higher than that in NH (P=.046 and P=.001, respectively). All tumors with NRAS(Q61R) expression exhibited uniform cytoplasmic positivity with or without accumulation in their cell membranes. Of the 15 tumors with NRAS(Q61R) expression, 13 cases showed NRAS(A182G) in direct sequencing, whereas all of the tumors without NRAS(Q61R) expression were negative for the mutation. There were no tumors with overlapping expression of NRAS(Q61R) and BRAF(V600E). In reference to the direct sequencing, sensitivity and specificity of the NRAS(Q61R) IHC were 100% and 98%, respectively. In conclusion, NRAS(Q61R) IHC is a highly sensitive and specific tool that is useful for differentiating follicular-patterned thyroid tumors.

Branchial Cleft-Like Cysts Involving 3 Different Organs: Thyroid Gland, Thymus, and Parotid Gland.

Abstract Branchial cleft cysts (BCCs) are also named lateral cervical cysts and widely acknowledged as being derived from embryonic remnants. Lymphoepithelial cysts (LECs) generally show microscopic features that are identical to those of BCCs, and rarely occur at unusual sites or organs. A case of multiple cysts arising in both lobes of the thyroid gland, thymus, and right parotid gland in a 41-year-old man is reported. Clinically, the patient presented with Hashimotos thyroiditis for about 20 years and had past histories of idiopathic thrombocytopenic purpura and severe respiratory infection. This case is unusual in that multiple cysts arose synchronously and/or heterochronously and grew, increasing their sizes in these different organs. Microscopic examinations revealed that all of the cysts were composed of squamous epithelium, dense lymphoid tissue with germinal centers, and a fibrous capsule. These findings corresponded to those of BCCs or LECs. It is notable that the histopathological features were nearly the same in the individual organs. A review of the literature disclosed no previous such reported cases. The etiology is unknown. However, based upon the similar histopathological features of all the excised specimens, common immune and/or hematopoietic disorders may have contributed to their occurrence and development in association with putative genetic abnormalities.

Localized Langerhans cell histiocytosis of the thymus with BRAF V600E mutation: a case report with immunohistochemical and genetic analyses ☆

We report a case of localized Langerhans cell histiocytosis characterized by clonal aggregation of Langerhans cells in the thymus and identified with molecular genetic study. A 43-year-old Japanese woman was found to have an anterior mediastinal mass by radiologic studies. Laparoscopy-assisted biopsy was subsequently performed. Histologically, we found subtle nodules scattered in the thymus consisting of aggregated Langerhans cells, which caused destruction of Hassall corpuscles. These Langerhans cells were immunohistochemically positive for S-100, CD1a, and CD207/langerin. Using allele-specific polymerase chain reaction and immunohistochemistry with mutation-specific antibody VE1, the BRAF V600E mutation was identified in aggregated Langerhans cells. At the medical follow-up, the thymic tumor had spontaneously regressed; however, identification of oncogenic BRAF mutation supports the neoplastic nature of the current case.

Primary Cervical Leiomyoma with Remarkable Calcification and Ossification

We encountered a patient with primary cervical leiomyoma with remarkable calcification and ossification. A 68-year-old man presenting with induration and swelling of the left submandibular region was found to have nodular lesions with calcifications in the left submandibular region and the upper mediastinum on CT. Fine needle aspiration biopsies (FNAB) of the left submandibular lesion revealed no malignancy. Resection was performed for definitive diagnosis and treatment. The resected specimen contained a solid tumor, which was markedly calcified and ossified on the cut surface. Histopathological examination showed proliferating spindle cells in a tangled and crossed arrangement. Immunohistochemically, the spindle cells were stained intensely with α-SMA and h-caldesmon, consistent with smooth muscle cells. These findings led to a definitive diagnosis of leiomyoma with calcification and ossification. This is extremely rare and the preoperative differentiation from other tumors of the head and neck was very difficult. By resection of the submandibular tumor, both definitive diagnosis of leiomyoma by histopathological and immunohistochemical analyses and treatment could be carried out. However, as the tumor in the upper mediastinum was most likely to be leiomyoma with calcification, he did not wish to undergo its biopsy and resection immediately. We have continued the follow-up.

Low frequency of PAX8-PPARγ rearrangement in follicular thyroid carcinomas in Japanese patients

Paired‐box gene 8 (PAX8)‐peroxisome proliferator‐activated receptor‐γ (PPARγ) gene fusion has been identified at significant frequency in follicular thyroid carcinomas (FTCs) with cytogenetically detectable translocation t(2;3)(q13;p25). This represents a possible specific molecular marker for follicular carcinoma. In this study, we examined PAX8‐PPARγ rearrangement in 24 FTC samples from Japanese patients by reverse transcribed‐polymerase chain reaction (RT‐PCR) using two upstream PAX8 primers located in exons 7 and 8 and a downstream primer in exon 1 of PPARγ. The fusion gene was detected in only one of 24 FTCs (4%). The FTC with PAX8‐PPARγ rearrangement from a 56‐year‐old man showed a product consistent with fusion between exon 8 of PAX8 and exon 1 of PPARγ. It was confirmed by direct sequencing. This FTC was histologically encapsulated, composed of trabeculae and small follicles and had complete penetration of the capsule by tumor tissues (minimally invasive type). The frequency of the fusion gene in this study was much lower than the 29–63% noted in reports from other countries suggesting that FTCs in Japanese patients may have a special genetic background, and that the high iodine intake from a typical Japanese diet might influence the frequency of the fusion gene in FTCs.

Multicentric occurrence of multiple papillary thyroid carcinomas –HUMARA and BRAF mutation analysis

Papillary thyroid carcinomas (PTCs) occasionally form multiple tumor foci in different sites of the same thyroid gland. However, it is controversial whether discrete nodules of PTC arise independently (multicentric occurrence) or are seeded from a single tumor via lymphatic channels (intraglandular metastasis). In order to determine the clonal origin of multiple PTCs, we examined X‐chromosome inactivation patterns using a human androgen receptor gene‐based assay (HUMARA) and the BRAF mutation using allele‐specific PCR (AS‐PCR) in 32 microdissected cancerous tissues from 14 Japanese women with multifocal PTC. All tumor foci were greater than 3 mm in size and met the criteria for microscopic classical PTC. Samples from 13 of the 14 patients were informative based on HUMARA. Tumor foci from two cases (15.4%) displayed a discordant X‐chromosome inactivation pattern. Foci from the other 11 cases (84.6%) showed a concordant inactivation pattern of the X‐chromosome. AS‐PCR indicated that BRAF mutational status between the tumor foci was discordant in three (25%) and concordant in nine (75%) of 12 available cases. When the results of these two molecular analyses were combined, 28.6% of the cases were discordant in X‐chromosome inactivation pattern and/or BRAF mutation, suggesting multicentric origin. Some of the remaining concordant cases also may be of multicentric origin. These results support a hypothesis that multicentric occurrence in multiple PTCs may be common, possibly greater than 30%. Although the exact mechanism of multicentric occurrence is still unclear, our findings contribute to the understanding the histogenesis of papillary thyroid carcinoma.

Well-differentiated neuroendocrine tumour of the breast showing peculiar endovascular spread.

Sir: Spread of an intravascular tumour embolus from a primary lesion can be found in some cancers: intraportal spread of hepatocellular carcinoma, postcaval spread of renal cell carcinoma, and so on. However, to the best of our knowledge, such a finding in breast cancers has not previously been reported in the English literature. The WHO classifies mammary carcinomas with neuroendocrine (NE) features as a special tumour entity, representing <1% of invasive breast carcinomas, and recognises three subtypes: (i) NE tumor (NET), well differentiated; (ii) NE carcinoma, poorly differentiated; and (iii) invasive carcinoma with NE differentiation. Herein, we describe the first case of a well-differentiated mammary NET with extensive intravenous spread. The patient, a 42-year-old premenopausal Thai woman, presented with a palpable mass in the subareolar portion of the left breast. Ultrasonography revealed a sharply marginated, hypoechoic left breast tumour showing heterogeneous internal echoes, with a cranially extending lumen-like structure filled with solid tumour with similar echoic findings (Figure 1A). On MRI, these lesions appeared as an oval-shaped mass and a continuous intravenous occupying lesion, respectively, both of which were strongly enhanced during the early phases of the dynamic study (Figure 1B). These images suggested an invasive cancer with a tumour thrombus. Systemic CT and bone scintigraphy detected no other suspicious lesions. Ultrasound-guided, fine needle aspiration of the breast mass yielded a cytological diagnosis of carcinoma. The cut surface of the lumpectomy specimen contained well-circumscribed, mixed brownish-red and grey-whitish, solid tumour nodules, measuring up to 17 9 15 mm in size. Histopathologically, the tumour was composed of a solid invasive growth of carcinoma cells with a peripheral palisading arrangement and a highly vascular stroma (Figure 2A,B). Haemorrhage was marked in the lesions. Carcinoma cells were polygonal or, occasionally, spindle-shaped with finely granular, slightly eosinophilic cytoplasm (Figure 2B). Their nuclei had ovoid or irregular shapes, a finely granular chromatin pattern, and small nucleoli. Mitotic figures were seen in seven of 10 high-power fields. An in-situ component composed of carcinoma cells with the same histological features was locally observed near the invasive cancer nests (Figure 2C). Massive tumour embolization within prominently dilated veins, spreading from the primary focus, was confirmed by the elastic Van Gieson method (Figure 2A,D). Focal lymphatic permeation