Malignant melanoma arising from an end ileostomy

Abstract

A 65-year-old woman with a history of proctocolectomy and end ileostomy for ulcerative colitis was referred to our clinic with a slowly growing mass around her ileostomy. She did not report any systemic symptoms. On examination, an exophytic mass was observed around her ileostomy and hard lymph nodes palpated in her groins bilaterally. Punch biopsy of the lesion established a diagnosis of invasive melanoma. Positron emission tomography revealed regional metastatic lymphadenopathy in the right axilla and both groins. There was no evidence of distant metastatic disease. The patient then underwent wide local excision of her ileostomy with bowel resection and ileostomy re-siting, bilateral complete ilioinguinal lymphadenectomy and a right Level III axillary dissection. She is doing well postoperatively and receiving adjuvant systemic therapy with BRAF and MEK inhibitors, now 17 months later with no signs of recurrent disease.

Background

Swellings and masses at stomas are clinically important findings that should be thoroughly assessed by healthcare providers.

Case presentation

A 65-year-old woman with a history of proctocolectomy and end ileostomy for ulcerative colitis 35 years prior was referred to our clinic in January of 2018 with a slowly growing mass around her ileostomy. She had noticed a small non-pigmented lesion at this site 4 months earlier. She did not report any systemic symptoms. On examination, an exophytic mass was observed around her ileostomy (figure 1) and hard lymph nodes were palpated bilaterally in her groins. The stoma was not obstructed either clinically or on digitation.

Figure 1.

Melanoma arising from the patients undergone end ileostomy.

Investigations

Punch biopsy of the lesion demonstrated an ulcerated malignant melanoma with a depth greater than 1 mm. Fine needle aspiration of her inguinal lymph nodes revealed metastatic malignant melanoma bilaterally. Positron emission tomography (PET) established metastatic lymphadenopathy in the right axilla and both inguinal regions and at the level of the left external iliac without evidence of visceral disease (figure 2). There was no evidence of intracranial metastatic disease on MRI of her brain, staging her at TxN3M0 (Stage IIIC).

Figure 2.

Positron emission tomography scan demonstrating uptake in right axilla (1), ileostomy site (2), and both inguinal regions (3 and 4).

Differential diagnosis

Swellings, masses and skin changes at stoma sites can be attributed to both benign and malignant aetiologies. Typical considerations include local irritation, granulation tissue, pyoderma gangrenosum and various malignancies including primary or metastatic adenocarcinoma as well as other less common malignancies such as in this example, melanoma.

Treatment

The patient was presented at multidisciplinary oncology rounds and after much discussion, the decision was made to proceed with surgical resection and nodal clearance followed by adjuvant therapy. The patient subsequently underwent a wide local excision of her ileostomy with small bowel resection and ileostomy resiting, bilateral complete ilioinguinal lymphadenectomy (this included both a superficial femoral node dissection as well as deep iliac and obturator node dissection bilaterally) and a level I–III right axillary dissection. Postoperatively, she recovered well and her pathology report demonstrated multiple dermal and mucosal/intramural deposits of metastatic melanoma in the vicinity of the ileostomy (figure 3a); margins of excision were negative (figure 3a). Metastatic melanoma was identified in one attached lymph node. Metastatic melanoma was demonstrated in 5 of 15 nodes without extranodal extension (ENE) in the left ilioinguinal region and 2 of 10 nodes without ENE in her right ilioinguinal region. In the level I–III axillary lymph node dissection, 1 out of 14 lymph nodes was positive for malignant melanoma and had ENE present (figure 3b). She was quite a thin patient and did not have much nodal tissue in the axilla, but all nerves and vessels were fully cleared including a level III dissection with transection of the pectoralis minor muscle and clearance of all the nodes inferior to the subclavian vein all the way to Haldstead’s ligament. Genetic testing determined the melanoma to be positive for the BRAF V600K mutation.

Figure 3.

(A) 2× magnification, H&E stain of mucocutaneous junction of the stoma. Transition from squamous to columnar cells marked with arrow. Melanoma cells marked with star. (B) 10× magnification H&E stain of lymph node positive for malignant disease.

CT scan performed 2 months postoperatively demonstrated several small indeterminate pulmonary lesions. These were closely followed and have now fully resolved with no progression of disease. It is now 17 months later and she still remains disease free. She was commenced on adjuvant targeted therapy with dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) 4 weeks after surgery and continued and tolerated treatment well.

Outcome and follow-up

She has tolerated treatment well and most recent PET scan, 6 months post-treatment initiation, does not demonstrate PET avid disease, suggestive of a complete radiological response. She will continue treatment with these targeted therapies and an ongoing surveillance strategy.

Discussion

Malignant melanoma occurring at ostomies is a very rare occurrence only having been reported in two other patients in published literature.^{1 2} Interestingly, in both of these cases, the patients had undergone end ileostomies for ulcerative colitis several decades earlier as with our case (table 1). These previous reports have speculated that chronic irritation at the mucocutaneous junction could be a causal factor in these isolated cases.¹ Both the time delay and the histopathological findings suggesting that the melanoma is arising from the mucocutaneous junction support this theory.

Table 1.

Reported cases of melanoma arising at ileostomies

Publication	Date	Age	Age of ileostomy	Treatment	Outcome
Warrier et al 1	2011	92	44 years	Surgical resection and stoma resiting, no adjuvant due to age	Survival at 1 year
Chan et al 2	2012	66	37 years	Wide local excision and groin dissection, no adjuvant therapy	Survival at 2 years
Gilbert et al	2019	65	35 years	Surgical resection and stoma resiting, axillary and groin dissection with adjuvant therapy	Survival at 1.5 years

Primary malignancies arising from ileostomy are rare occurring at an estimated rate of 200–400 per 100 000 ileostomies.^{3 4} This case serves as an important reminder that swellings, masses and skin changes at stomas are important findings that should be thoroughly assessed by healthcare providers to ensure a malignancy is not overlooked.

Learning points.

• Malignancies can arise at ostomies and should always be considered when new swellings, masses or skin changes occur at the site of an ostomy.

• Long-term survival can be achieved with targeted therapy in patients with advanced melanoma.

• There may be a relationship between long-term ostomies and melanoma risk.