Translate this page into:
Metastatic Spread to Breast in a Case of Mucinous Adenocarcinoma Appendix Detected on 18F-FDG PET-CT scan
Address for correspondence: Dr. Aishwarya Wagle, Department of Nuclear Medicine, P.D. Hinduja Hospital and Medical Research Centre, Mahim West, Mumbai – 400 016, Maharashtra, India. E-mail: aishwaryawagle47@gmail.com
-
Received: ,
Accepted: ,
This article was originally published by Wolters Kluwer - Medknow and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Appendiceal adenocarcinomas are rare invasive gastrointestinal neoplasms, with higher propensity to metastasize to lymph nodes and peritoneum, whereas other common sites include liver and lung. Metastases to the breast are exceptionally rare in appendiceal neoplasms, with limited data in literature. We present the case of a recurrent mucinous adenocarcinoma of the appendix with clinically occult breast, skeletal, and nonregional nodal metastases detected on fluorine-18-fluorodeoxyglucose positron emission tomography–computed tomography scan.
Keywords
Breast metastases
carcinoma appendix
18F-fluorodeoxyglucose positron emission tomography–computed tomography
Introduction
Adenocarcinoma of the appendix is a rare malignancy. The most common sites of metastases are regional lymph nodes and the peritoneum, whereas involvement of the lungs and liver is rarely reported. Flourine-18-fluorodeoxyglucose positron emission tomography–computed tomography (¹⁸F-FDG PET-CT) is useful in evaluating the extent of malignant disease and can often detect clinically occult, metabolically active metastatic sites. However, the mucinous variant of adenocarcinoma may exhibit low FDG uptake at metastatic sites. This report presents a case of recurrent appendiceal carcinoma with unusual metastatic sites, emphasizing the diagnostic utility of ¹⁸F-FDG PET-CT in the evaluation of such cases.
Case Report
A 69-year-old female presented with complaints of the right lower abdominal pain. Abdominal ultrasonography (USG) suggested sealed-off perforated appendicitis, for which she underwent laparoscopic appendicectomy. Surgical histopathology revealed a well-differentiated mucinous adenocarcinoma of the appendix (pT3). The patient further underwent right hemicolectomy, right oophorectomy, and peritonectomy, which were tumor free on histopathology. A year later, she developed abdominal pain with the appearance of a cutaneous nodule over the incision site. She underwent excision of the umbilical nodule with incisional hernia repair, and the histopathology of the abdominal nodule revealed a metastatic well-differentiated mucinous adenocarcinoma. She further received radiotherapy to the anterior abdominal wall. After a symptom free period of 3 years, she came to us presenting with a hard mass in the right inguinal region. USG revealed an inguinal nodal mass suspicious for metastasis. Fluorine-18-fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET-CT) scan [Figure 1] was performed for restaging to assess for other metastatic disease sites, and it showed a FDG-avid enhancing irregular lobulated right inguinal nodal mass measuring 3.6 cm × 3.8 cm with maximum standardized uptake value (SUVmax) of 20, and a sclerotic lesion in the body of the L2 vertebra with SUVmax 5, which appeared metastatic. It also revealed a subcentimeter-sized well-defined enhancing nodule in the right breast lateral aspect measuring 8 mm × 5 mm and a mildly enlarged right axillary node measuring 1.2 cm × 0.8 cm with low-grade FDG uptake, which appeared suspicious; however, a second primary breast origin was to be ruled out. Biopsy of the right inguinal nodal lesion confirmed the metastasis of a well-differentiated mucinous adenocarcinoma. Biopsy and immunohistochemistry (IHC) of the right breast lesion revealed a well-differentiated mucinous adenocarcinoma with tumor cells immunoreactive for CK20, CEA, CDX2, and SATB2 and negative for CK7, GATA3, ER, PR, and HER-2, suggestive of metastases from mucinous adenocarcinoma of the appendix. The patient then received radiation to the right inguinal region and chemotherapy.
Discussion
Primary appendiceal neoplasms are a rare entity forming as low as 1% of all gastrointestinal tumors. Adenocarcinoma of the appendix comprises ~20% of all appendiceal neoplasms, of which mucinous variant is the most common.[1] Most patients present with appendicitis and diagnosis is incidentally obtained after appendectomy as seen in our patient. Appendiceal carcinomas are known to metastasize via lymphatic channels to regional nodes or peritoneal spread. Other rare sites reported include liver and lungs.[2] However, in our patient, we came across unusual metastatic sites of disease recurrence like breast, nonregional right inguinal and axillary nodal lesions, and bone metastasis, of which breast, axilla, and bone were occult lesions detected on 18F-FDG PET-CT scan. Metastatic involvement of the breast from primary appendiceal adenocarcinoma is an exceptionally rare phenomenon, with only a few cases documented in the literature.[34] Furthermore, we found that some lesions in our patient showed high FDG avidity, while others showed low-grade FDG uptake. This interlesional heterogeneity of FDG uptake in different metastatic sites of mucinous appendiceal adenocarcinomas correlates with the varied mucin content in the tissue, where lesions with high mucin content may show low FDG uptake, and lesions with low mucin content can show high FDG avidity.[5] We, nuclear medicine physicians, must keep this in mind when reporting such cases.
Conclusion
Our case report, thus, highlights that mucinous appendiceal adenocarcinoma could recur in unusual sites like breast, nonregional nodes, and bone, and 18F-FDG PET-CT scan is useful in detecting occult sites.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Nil.
References
- Molecular classification of appendiceal adenocarcinoma. J Clin Oncol. 2023;41:1553-64.
- [Google Scholar]
- A 25-year review of adenocarcinoma of the appendix. A frequently perforating carcinoma. Dis Colon Rectum. 1988;31:145-50.
- [Google Scholar]
- Appendiceal adenocarcinoma presenting as palpable breast masses. ACG Case Rep J. 2024;11:e01385.
- [Google Scholar]
- FDG PET evaluation of mucinous neoplasms: Correlation of FDG uptake with histopathologic features. Am J Roentgenol. 2000;174:1005-8.
- [Google Scholar]