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Anal cancer with isolated ischial fossa lymph node metastases: A rare entity in the oligometastatic dilemma

1 Department of Radiation Oncology, King Hussein Cancer Center, Amman, Jordan
2 Department of Radiology, King Hussein Cancer Center, Amman, Jordan
3 Department of Nuclear Medicine, King Hussein Cancer Center, Amman, Jordan
4 Department of Radiation Oncology, Afia Radiotherapy and Nuclear Medicine Center, Amman, Jordan

Date of Submission24-Dec-2019
Date of Decision11-Feb-2020
Date of Acceptance06-May-2020
Date of Web Publication26-Nov-2020

Correspondence Address:
Fawzi Abuhijla,
Department of Radiation Oncology, King Hussein Cancer Center, PO Box: 1269, Amman 11941
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrt.JCRT_1158_19

 > Abstract 

Carcinoma of the anal canal is relatively rare cancer with a low propensity for metastasis. A literature review identifies two cases with ischial fossa metastases from anal cancer. The authors present the case of a 62-year-old male with moderately differentiated squamous cell carcinoma of the anal canal who presented with isolated ischial fossa lymph node (LN) confirmed by fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography and pelvic magnetic resonance imaging. The patient was treated with concurrent chemoradiation. Ischial fossa LN was included in the high-dose radiation volume. Posttreatment imaging showed complete clinical response. This case highlights a rare metastatic site from anal cancer treated successfully with primary chemoradiation and shows an example of tailored treatment approach of oligometastatic disease from anal cancer.

Keywords: Anal cancer, chemoradiation, ischial fossa lymph node, metastatic disease, personalized medicine

How to cite this URL:
Mohamad I, Abuhijlih R, Alkaldi M, Al-Ibraheem A, Khatib S, Abuhijla F. Anal cancer with isolated ischial fossa lymph node metastases: A rare entity in the oligometastatic dilemma. J Can Res Ther [Epub ahead of print] [cited 2022 Aug 7]. Available from: https://www.cancerjournal.net/preprintarticle.asp?id=300996

 > Introduction Top

Anal cancer accounts for 2% of all gastrointestinal malignancies. Most of the newly diagnosed cases present with locally advanced stage, while metastatic disease accounts only for <15% at presentation.[1] This case report expresses oligometastatic presentation from anal cancer. It also provides an example of personalized approach for treating oligometastatic anal cancer with curative intent.

 > Case Report Top

A 62-year-old male was, accidently, found to have anal mass during hemorrhoidectomy. He underwent local excision of the anal mass. Pathology review at our center demonstrated invasive moderately differentiated squamous cell carcinoma (SCC) resected with free margins. The tumor size was 4 cm and there was imaging prior to the local excision procedure. Colonoscopy was completed and showed no evidence of gross residual disease in the anal canal, no other findings in the remaining examination.

Magnetic resonance imaging (MRI) of the pelvis and computed tomography (CT) scan of the chest, abdomen, and pelvis were performed for staging and demonstrated postoperative changes in the anal canal, left ischial fossa lymph node (LN) just anterior to the left gluteus muscle, measures 1.6 cm with no other pelvic or inguinal LN enlargement.

Positron emission tomography (PET) study [Figure 1] showed a suspicious hypermetabolic left ischial fossa LN anterior to the gluteus muscles with a maximum standard uptake value of 3 with no evidence of other metastatic disease outside the pelvis.
Figure 1:18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography scan: Maximum intensity projection image (a) shows focal area of abnormal increased fluoro-2-deoxy-D-glucose uptake in the left side of the pelvis (arrow). Corresponding axial positron emission tomography scan (b) and fused positron emission tomography/computed tomography (c) show a suspicious hyper metabolic lesion in the left ischial fossa laterally located in the fatty pad just anterior to gluteus muscles. This has been retrospectively correlated to 1.6 cm soft tissue nodule on corresponding axial computed tomography scan (d)

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The case was reviewed at the multidisciplinary tumor board. Given the technical challenges to obtain biopsy in this area and no history of pelvic trauma, fat necrosis, or infection, the recommendation was to proceed with concomitant chemoradiation.

The patient was treated with intensity-modulated radiation therapy (IMRT) plan consisted of 30 fractions (fx) of 1.8 gray (Gy) per fraction delivered in two phases: Phase I as 36 Gy in 20 fx directed at primary tumor bed and regional and metastatic ischial fossa LNs and Phase II as 18 Gy in 10 fx encompassed tumor bed and left ischial fossa LN to get the total dose up to 54 Gy as shown in [Figure 2].
Figure 2: (a) Radiotherapy plan for Phase I as 36 Gy/20 fractions. (b) Phase II delivering boost to tumor bed and ischial lymph node as 18 Gy/10 fractions

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Concurrent chemotherapy was given with continues 5-FU 1000 mg/m2/day (days 1–4 and 29–32) and mitomycin C 10 mg/m2 (days 1 and 29), without significant toxicity. Postchemoradiotherapy pelvic MRI done 12 weeks posttreatment showed complete radiological response to chemoradiotherapy as shown in [Figure 3].
Figure 3: (a) Pretreatment magnetic resonance scan illustrating ischial lymph node enlargement. (b) Posttreatment resolution of the ischial lymph node

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Currently, the patient is disease free after 2 years of completion treatment and on regular follow-up with clinical examination, colonoscopy, and pelvic MRI and CT scans.

 > Discussion Top

Our patient presents a case of isolated ischial fossa LN metastasis as the only site of metastasis in patient with SCC of anal cancer. This case is unique because it represents a rare site of metastasis without any visceral disease and outlines treatment approach for this rare entity. The regional spread from anal cancers is likely to mesorectal, internal iliac, external iliac, and inguinal LNs. However, there is no likely explanation for inferior gluteal LN from anal cancer,[2] except lymphatic spread from internal iliac vessels which could be related to obstruction of the primary lymphatic channels for anal cancer. As known, ischial fossa LN is considered as distant metastases rather than regional disease as per the AJCC 8th ed.ition TNM staging and not routinely included in the radiation elective nodal volume.[3]

Uzun et al. have reported the use of MRI to identify gluteal LN. In their report, 6 out of 22 patients have had pelvic malignancies, 2 of them were diagnosed with anal canal SCC.[4]

The use of PET scan in anal cancer showed higher sensitivity for LN staging and change in intent of treatment,[5] with subsequent impact on radiation target volume delineation.[6]

Given the close location of metastatic LN to radiation therapy target volume, challenges with obtaining pathological confirmation due to proximity to neurovascular structures, the ischial fossa was included in the elective target volume and boosted gross ischial fossa LN to full radiation dose concurrently with mitomycin and 5FU-based chemotherapy.

The use of IMRT in anal cancer showed significant decrease in radiation toxicity and provided a unique tool for local therapy for metastatic disease.[7] Definitive treatment intent anal SCC with limited metastatic volume has shown better progression-free survival as reported by Gnanajothy et al.[8]

In this case, radiation therapy volume was tailored using IMRT to include the metastatic ischial fossa LN in addition to the standard radiotherapy volume for anal cancer.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 > References Top

Dewdney A, Rao S. Metastatic squamous cell carcinoma of the anus: Time for a shift in the treatment paradigm? ISRN Oncol 2012;2012:756591.  Back to cited text no. 1
Llauger J, Palmer J, Pérez C, Monill J, Ribé J, Moreno A. The normal and pathologic ischiorectal fossa at CT and MR imaging. Radiographics 1998;18:61-82.  Back to cited text no. 2
Myerson RJ, Garofalo MC, El Naqa I, Abrams RA, Apte A, Bosch WR, et al. Elective clinical target volumes for conformal therapy in anorectal cancer: A radiation therapy oncology group consensus panel contouring atlas. Int J Radiat Oncol Biol Phys 2009;74:824-30.  Back to cited text no. 3
Uzun Ç, Erden A, Atman ED, Üstüner E. Use of MRI to identify enlarged inferior gluteal and ischioanal lymph nodes and associated findings related to the primary disease. Diagn Interv Radiol 2016;22:314-8.  Back to cited text no. 4
Winton Ed, Heriot AG, Ng M, Hicks RJ, Hogg A, Milner A, et al. The impact of 18-fluorodeoxyglucose positron emission tomography on the staging, management and outcome of anal cancer. Br J Cancer 2009;100:693-700.  Back to cited text no. 5
Rusten E, Rekstad BL, Undseth C, Al-Haidari G, Hanekamp B, Hernes E, et al. Target volume delineation of anal cancer based on magnetic resonance imaging or positron emission tomography. Radiat Oncol 2017;12:147.  Back to cited text no. 6
Scher ED, Ahmed I, Yue NJ, Jabbour SK. Technical aspects of radiation therapy for anal cancer. J Gastrointest Oncol 2014;5:198-211.  Back to cited text no. 7
Gnanajothy R, Warren GW, Okun S, Peterson LL. A combined modality therapeutic approach to metastatic anal squamous cell carcinoma with systemic chemotherapy and local therapy to sites of disease: Case report and review of literature. J Gastrointest Oncol 2016;7:E58-63.  Back to cited text no. 8


  [Figure 1], [Figure 2], [Figure 3]


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