SOX11 is a sensitive and specific marker for pulmonary high-grade neuroendocrine tumors

The diagnostic utility of SOX11 Immunohistochemical expression in malignant peripheral nerve sheath tumors and their potential mimickers

Malignant peripheral nerve sheath tumor (MPNST) comprises 5-10 % of all soft tissue sarcomas, and their diagnosis may be challenging given the absence of robust immunohistochemical and molecular signatures. SOX11 expression has previously been shown to be present in a small subset of MPNST. In the present study, we evaluated a group of MPNST for SOX11 expression by immunohistochemistry. We similarly assessed a group of benign and malignant spindle cell tumors that are in the differential diagnosis of MPNST, to more expansively establish the specificity of the antibody. In total, 59 MPNSTs, 27 synovial sarcomas, 19 leiomyosarcomas, 19 rhabdomyosarcomas, 19 solitary fibrous tumors, 4 clear cell sarcomas of soft tissue, 19 malignant melanomas, 22 schwannomas (11 classical, 11 cellular), 9 neurofibromas (4 plexiform, 2 atypical, and 3 classical) and 9 nodular fasciitis were included. SOX11 was strongly positive in 41 of 59 MPNSTs (67 %), 16 of 27 synovial sarcomas (59 %), 11 of 19 rhabdomyosarcomas (58 %), 1 of 4 clear cell sarcomas (25 %), and 5 of 9 nodular fasciitis (56 %). In contrast, neurofibromas(n=11)), schwannomas (n=22), leiomyosarcomas (n=22), and solitary fibrous tumors (n=19) were either negative or showed only weak and focal expression for SOX11. The sensitivity and specificity of strong SOX11 expression in differentiating MPNST from its mimickers were 70 % and 73 %, respectively. In conclusion, the diagnostic utility of SOX11 expression for MPNST is limited, but the absence of significant SOX11 expression in benign/atypical nerve sheath tumors is interesting and deserves further investigation.

Occult urothelial carcinoma with mediastinal metastasis: A case report

Occult urothelial carcinoma (UC), particularly with mediastinal metastases, is an uncommon clinical occurrence. The present study describes the unusual case of a 70-year-old male patient who developed mediastinal metastases from an occult UC. Histological evaluations and immunohistochemical features of the mediastinal tumor were indicative of UC; however, extensive imaging failed to identify the primary urological lesion. The findings suggest that mediastinal metastases from UCs, despite their rarity, should be considered in cases where patients with mediastinal tumors exhibit chest-related symptoms. Prompt pathological examinations are crucial for ascertaining the nature and origin of the tumor. Moreover, individualized treatment should be performed in strict accordance with the established oncology guidelines.

SOX11 Is an Effective Discriminatory Marker, When Used in Conjunction With CK20 and TTF1, for Merkel Cell Carcinoma: Comparative Analysis of SOX11, CK20, PAX5, and TTF1 Expression in Merkel Cell Carcinoma and Pulmonary Small Cell Carcinoma

CONTEXT.—

Distinction between Merkel cell carcinoma (MCC) and pulmonary small cell carcinoma (PSmCC) can be challenging, even with the aid of immunohistochemistry (IHC) analysis of CK20 and TTF1, as these tumors occasionally lack classic immunophenotypes (CK20+/TTF1- in MCC and CK20-/TTF1+ in PSmCC).

OBJECTIVE.—

To evaluate the diagnostic utility of SOX11 and PAX5 IHC for distinguishing MCCs from PSmCCs and compare it with that of CK20 and TTF1 IHC.

DESIGN.—

SOX11, PAX5, CK20, and TTF1 expression (pattern, intensity, and proportion of tumor cells expressing protein) was assessed in 31 primary and 16 metastatic MCCs and 20 primary and 9 metastatic PSmCCs.

RESULTS.—

SOX11 expression was present in all MCCs and was predominantly strong and diffuse. Only 19% of primary and 38% of metastatic MCCs exhibited diffuse PAX5 expression; none exhibited strong immunoreactivity. Strong and diffuse SOX11 expression was seen in less than 25% of primary and metastatic PSmCCs. PAX5 expression was rare in PSmCCs and was mostly weak and focal/patchy. SOX11 expression in at least 26% of tumor cells, with at least moderate intensity, favored the diagnosis of MCC over PSmCC (P < .001). Furthermore, SOX11 expression was more likely than CK20 expression to be strong or diffuse in sentinel lymph node (SLN) metastases of MCC, indicating that SOX11 is superior to CK20 for detecting tumor deposits in SLNs in MCC.

CONCLUSIONS.—

Our findings indicate that SOX11 not only is a powerful marker for distinguishing MCCs from PSmCCs, especially when used in conjunction with CK20 and TTF1, but also has utility for screening SLNs in MCC.

Insulinoma-Associated Protein 1 (INSM1): Diagnostic, Prognostic, and Therapeutic Use in Small Cell Lung Cancer

Small cell lung carcinoma (SCLC) is an aggressive and difficult to treat cancer. Although immunohistochemistry is not mandatory for a SCLC diagnosis, it might be required, especially in small samples. Insulinoma-associated protein 1 (INSM1) is expressed in endocrine and nervous tissues during embryogenesis, generally absent in adults and re-expressed in SCLC and other neuroendocrine neoplasms. Its high specificity propelled its use as diagnostic biomarker and an attractive therapeutic target. Herein, we aim to provide a systematic and critical review on the use of INSM1 for diagnosis, prognostication and the treatment of SCLC. An extensive bibliographic search was conducted in PubMed® focusing on articles published since 2015. According to the literature, INSM1 is a highly sensitive (75–100%) and specific (82–100%) neuroendocrine immunohistochemical marker for SCLC diagnosis. It can be used in histological and cytological samples. Although advantageous, its standalone use is currently not recommended. Studies correlating INSM1 expression and prognosis have disclosed contrasting results, although the expression seemed to entail a worse survival. Targeting INSM1 effectively suppressed SCLC growth either as a suicide gene therapy regulator or as an indirect target of molecular-targeted therapy. INSM1 represents a valuable biomarker for a SCLC diagnosis that additionally offers vast opportunities for the development of new prognostic and therapeutic strategies.