Metastatic melanoma presenting as undifferentiated tumour of unknown primary site: an immunohistochemical algorithm

Ali, Leila; Moldovan, Valentin Tiberiu; DEREWICZ, Diana; Ginghină, Octav; Sajin, Maria; Costache, Mariana

doi:10.31688/abmu.2019.54.4.08

Cited by 1 publication

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References 23 publications

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“…Therefore, considering the literature and the authors previous studies, it is desirable to add an anti-DOG1 antibody to the second or third batch of IHC testing. This avoids the misdiagnosis of a melanoma or germ tumor with partial c-KIT expression or a modified expression for S100 [ 30 , 31 , 32 ].…”

Section: ⧉ Discussionmentioning

confidence: 99%

Morphological and immunohistochemical diagnostic of extragastrointestinal stromal tumors – a 51 case series analysis

Moldovan¹,

Pătraşcu²,

Ali³

et al. 2022

Rom J Morphol Embryol

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Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the digestive tract, originating from structures differentiating towards Cajal cells. Due to their morphology and localization, the extragastrointestinal stromal tumors (EGISTs) can be a diagnostic challenge. We investigated a series of 51 EGISTs diagnosed in our institutions, aiming to explore the immunophenotypes and to analyze the process and the utility of the antibodies required for a positive diagnosis. Immunohistochemical examinations were done for pan-cytokeratin (pan-CK), Ki67, discovered on GIST1 (DOG1) protein and platelet-derived growth factor receptor alpha (PDGFRA), as necessary. The main tumor site was abdominal wall in 43 (84%) cases, most of the tumors showed spindle cell cellularity, followed by mixed and epithelioid type. Twenty-six cases revealed a full conventional immunohistochemical profile with DOG1 positivity. In 10 cases, c-KIT expression was absent but with the preservation of cluster of differentiation (CD)34 positivity, and eight cases were positive for PDGFRA. In our study, we found a subgroup of eight cases presenting in extra-abdominal settings (including one in lung and two in the head-and-neck area). We concluded EGISTs represent a histopathological and immunohistochemically challenging subgroup testing more often negative for c-KIT mutations and positive for PDGFRA compared to GIST. DOG1 remains the marker of choice regardless of tumor site, while CD34 and CD117 should be considered as adjuvants.

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Section: ⧉ Discussionmentioning

confidence: 99%