The Role of Immunohistochemistry in the Workup of Malignant Neoplasms of Unknown Primary Origin at Khartoum Oncology Hospital

Abstract

Background: Carcinoma of unknown primary origin (CUP) comprises various malignancies classified by detection of tissue-specific genes through immunohistochemistry (IHC). We aimed to explore the role of available immunohistochemical markers in diagnosing and classifying malignant neoplasms of unknown primary origin.Methods: A cross-sectional study included 141 patients diagnosed histologically as CUP and referred to the Histopathology and Immunohistochemistry Department, Khartoum Oncology Hospital, from 2012 to 2017. Hematoxylin and Eosin (H&E) and immune stained slides used in the workup were reviewed and classified into the main histologic types of CUP. Data were -analyzed by SPSS. Results: Out of 4436 cases, CUP represents (3.2%). The age group (60-69) years have the highest percentage (20.13%), with male predominance (51.77%). Lymph nodes represent (41.84%) followed by the liver (12.77%), spine (3.55%), and lungs (2.13%). Adenocarcinoma (75.89%) was the most common subtype, followed by undifferentiated neoplasm (14.18%), squamous cell carcinoma (7.09%), and carcinoma with neuroendocrine differentiation (2.84%). In 70 cases (49.6%) of the study cases, the primary site was determined, (17.7%) were given an only differential diagnosis, and in (32.6%) the origin remains unknown. Conclusions: CUP cases during the study period are infrequent (3.2%), and the primary origin was determined in nearly half of patients by the available immune markers. CUP’s common histological types were adenocarcinoma, undifferentiated neoplasm, squamous cell carcinoma, and carcinoma with neuroendocrine differentiation. The most common presenting sites were lymph node, liver, spine, and lungs.

Immunohistochemistry at rescue in the cancers of unknown primary origin

“…This research study was aimed to explore the role of all the available immunohistochemical markers in detecting malignancies of unknown primary origin. The present study covered 40 CUP cases out of 4026 cases diagnosed during the study period of 2019 to 2023, represents 0.99%, which is less than the other studies in which this ratio ranges between 3-5% [6,7] .…”

“…The biology of Cancer of Unknown Primary (CUP) remains somewhat unclear, but there are common biological features shared among CUP tumors. These characteristics include early metastasis from a clinically undetectable primary tumor, an unpredictable metastatic pattern, aggressive biological behavior, and clinical characteristics that make CUP a challenging and unique entity in cancer diagnosis and management [5,6] . Given that CUP is a common and challenging clinical problem, the role of IHC workup in CUP is crucial.…”

“…Given that CUP is a common and challenging clinical problem, the role of IHC workup in CUP is crucial. It aids in classifying tumors according to their broad type, subtype, and, if possible, the site of origin [6] . This classification provides significant benefits in diagnosing and managing CUP patients [6] .…”

“…It aids in classifying tumors according to their broad type, subtype, and, if possible, the site of origin [6] . This classification provides significant benefits in diagnosing and managing CUP patients [6] . Identifying patients with favorable disease through this approach is essential, as they may benefit from targeted treatments.…”

Soft tissue tumor of metastatic non-small cell lung carcinoma: A rare case report

“…But because there is already a suspected primary lesion in the lungs; as identified by CT-scan and compounded by the fact the from the microscopical slides of the tumor showed adenosquamous carcinoma, all of it correlate with each other and points to the direction of a lung metastasis. Also adding to the fact that there are limited resources in our facility that prevents us from easily doing the immunohistochemistry examination, we deemed that the diagnosis can be determined even without immunohistochemistry [ 14 ].…”