Branchioma: immunohistochemical and molecular genetic study of 23 cases highlighting frequent loss of retinoblastoma 1 immunoexpression

Bradová M, Thompson LD, Hyrcza M, Vaněček T, Grossman P, Michal M, Hájková V, Taheri T, Rupp N, Suster D, Lakhani S, Nikolov DH, Žalud R, Skálová A, Michal M, Agaimy A (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Virchows Archiv Springer Verlag (Germany)

DOI: 10.1007/s00428-023-03697-1

Abstract

Branchioma is an uncommon benign neoplasm with an adult male predominance, typically occurring in the lower neck region. Different names have been used for this entity in the past (ectopic hamartomatous thymoma, branchial anlage mixed tumor, thymic anlage tumor, biphenotypic branchioma), but currently, the term branchioma has been widely accepted. Branchioma is composed of endodermal and mesodermal lineage derivatives, in particular epithelial islands, spindle cells, and mature adipose tissue without preexistent thymic tissue or evidence of thymic differentiation. Twenty-three branchiomas were evaluated morphologically. Eighteen cases with sufficient tissue were assessed by immunohistochemistry, next-generation sequencing (NGS) using the Illumina Oncology TS500 panel, and fluorescence in situ hybridization (FISH) using an RB1 dual-color probe. All cases showed a biphasic morphology of epithelial and spindle cells with intermingled fatty tissue. Carcinoma arising in branchioma was detected in three cases. The neoplastic cells showed strong AE1/3 immunolabeling (100%), while the spindle cells expressed CD34, p63, and SMA (100%); AR was detected in 40–100% of nuclei (mean, 47%) in 14 cases. Rb1 showed nuclear loss in ≥ 95% of neoplastic cells in 16 cases (89%), while two cases revealed retained expression in 10–20% of tumor cell nuclei. NGS revealed a variable spectrum of likely pathogenic variants (n = 5) or variants of unknown clinical significance (n = 6). Loss of Rb1 was detected by FISH in two cases. Recent developments support branchioma as a true neoplasm, most likely derived from the rudimental embryological structures of endoderm and mesoderm. Frequent Rb1 loss by immunohistochemistry and heterozygous deletion by FISH is a real pitfall and potential confusion with other Rb1-deficient head and neck neoplasms (i.e., spindle cell lipoma), especially in small biopsy specimens.

Authors with CRIS profile

Abbas Agaimy Lehrstuhl für Allgemeine Pathologie und Pathologische Anatomie

Involved external institutions

Biopticka laborator s.r.o. CZ Czech Republic (CZ) University of Calgary CA Canada (CA) Univerzita Karlova v Praze / Charles University in Prague CZ Czech Republic (CZ) University of Queensland AU Australia (AU) Universitätsspital Zürich (USZ) CH Switzerland (CH) The State University of New Jersey (Rutgers) US United States (USA) (US) Regional hospital Kolin / Oblastní nemocnice Kolín CZ Czech Republic (CZ)

How to cite

APA:

Bradová, M., Thompson, L.D., Hyrcza, M., Vaněček, T., Grossman, P., Michal, M.,... Agaimy, A. (2023). Branchioma: immunohistochemical and molecular genetic study of 23 cases highlighting frequent loss of retinoblastoma 1 immunoexpression. Virchows Archiv. https://doi.org/10.1007/s00428-023-03697-1

MLA:

Bradová, Martina, et al. "Branchioma: immunohistochemical and molecular genetic study of 23 cases highlighting frequent loss of retinoblastoma 1 immunoexpression." Virchows Archiv (2023).

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