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Angiomyolipoma, oncocytoma, and retroperitoneal fibrosis
Published in J Kellogg Parsons, E James Wright, The Brady Urology Manual, 2019
Positive immunoreactivity for HMB-45: Characteristic for AMLPositive reaction rules out sarcoma.
Head and Neck Pathology
Published in John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford, Head & Neck Surgery Plastic Surgery, 2018
Ram Moorthy, Adrian T. Warfield, Max Robinson
For poorly differentiated tumours, IHC is required to render an accurate diagnosis. The initial panel of IHC is directed at identifying broad groups of tumours: carcinoma, melanoma, lymphoma and sarcoma. A pan-cytokeratin cocktail is used to demonstrate cytokeratin intermediate filaments, which is positive in virtually all carcinomas. S100, MelanA, HMB45 and Sox10 can be used to identify melanoma. CD45 (leucocyte common antigen), CD79a (B cell marker) and CD3 (T cell marker) are used to identify lymphoma. Sarcomas are more variable and panels are formulated based on morphological clues. Antibodies for desmin and vimentin are often used to start the process of investigation.
Malignant Neoplasms of the Colon
Published in Philip H. Gordon, Santhat Nivatvongs, Lee E. Smith, Scott Thorn Barrows, Carla Gunn, Gregory Blew, David Ehlert, Craig Kiefer, Kim Martens, Neoplasms of the Colon, Rectum, and Anus, 2007
On endoscopic examination these lesions may appear amelanotic but may have enough pigmentation to be easily recognizable on gross or microscopic examination. Intussusception of the colon, multiple colonic polyps, and fungating masses resembling colon carcinoma have been described on endoscopy. Colonoscopy is not only the most reliable study but also offers the benefit of obtaining tissue for diagnosis. Special stains such as nuclear S-100 and cytoplasmic HMB-45 may be necessary to secure the diagnosis.
Matched analysis of the prognosis of amelanotic and pigmented melanoma in head and neck
Published in Acta Oto-Laryngologica, 2020
Wei Guo, Gaofei Yin, Hongfei Liu, Hanyuan Duan, Zhigang Huang, Xiaohong Chen
The histopathological diagnosis of melanoma is based on the identification of intracellular melanin. Therefore, it is often difficult to make a final diagnosis of non-pigmented lesions, and tumour cells are diverse in morphology. These cell types can present epithelioid, fusiform, plasmacytoid, rhabdomyoid or polynuclear morphology alone or in combination [13]. It is difficult to make a definite diagnosis of AM during intraoperative freezing, and an immunohistochemical study is necessary to make a definite diagnosis. Immunohistochemical staining is very valuable for diagnosis, especially for S100, HMB-45 and Melan-A. The sensitivity of S100 was 97–100%, but the specificity was 75–87% [14]. Melan-A is a highly sensitive and specific marker, especially for cutaneous malignant melanoma and its metastasis, but it is inferior to HMB-45 in non-cutaneous malignant melanoma [15]. It has been reported [16] that HMB-45 may be more sensitive to primary oral and nasal melanoma than any other marker because it shows significantly higher staining intensity.
Malignant Perivascular Epitheloid Cell Tumor with an Unusual Immunophenotype in a Ten-Year-Old Child
Published in Fetal and Pediatric Pathology, 2019
Nives Jonjic, Jelena Roganovic, Nedeljka Glavan, Ita Hadzisejdic, Irena Seili-Bekafigo
PEComas are characterized by positive immunostaining for markers of both melanocytic and myoid differentiation [3]. In the Folpe et al. review nearly all tumors were immunoreactive for HMB-45 (100%) and/or Melan A (41%) [7] but that was not the case in our report. The negativity for HMB-45 has already been reported [17–20]. According to some authors the variability in HMB-45 expression could be related to the TSC, given that the regions that have been found to be linked to TSC in different families map to the positions of three enzymes, phenylalanine hydroxylase, tyrosinase, and dopamine-beta-hydroxylase. Disorders of these biochemical pathways might be involved in the conversion of phenylalanine to catecholamine neurotransmitters or melanin [17].
Thrombosed orbital arteriovenous malformation in a patient with lymphangioleiomyomatosis
Published in Orbit, 2022
Elzbieta Mechel, Ann Q. Tran, Andrea Tooley, Michael Kazim
Due to concern for a LAM-related orbital tumor, the patient underwent a lateral orbitotomy through a canthotomy and cantholysis approach (Figure 2a). The tumor appeared to originate adjacent to and enlarging the inferior orbital fissure. The mass was 2 × 1 cm, well-circumscribed, rubbery, cystic, and focally hemorrhagic (Figure 2b). Histopathologic analysis revealed congested blood vessels with a thick smooth muscle component and inflammatory cells, consistent with a thrombosed arteriovenous malformation (AVM) (Figure 3). There was no evidence of spindle-shaped or epithelioid LAM cells. Staining for melanocytic markers, Melan-A and Human Melanoma Black (HMB)-45, typically expressed in LAM, was negative.