Adenocarcinomas presenting as abdominal wall masses

Abstract

Patients with abdominal wall masses as primary malignant tumours or metastatic disease are rare. Thorough evaluation with biopsy and imaging is required prior to surgical resection for treatment planning. We present a case series of three patients who presented with abdominal adenocarcinoma of unknown primary origin. All patients ultimately underwent surgical resection and final pathology showed a gynaecological origin for these tumours. Multidisciplinary management is required for these rare and complex tumours.

Background

Soft tissue masses are common to encounter and range from superficial lipomas and abscesses to metastatic disease from underlying malignancy. In the abdominal wall, the differential diagnosis of soft tissue tumours can be organised into trauma-related masses, iatrogenic, infectious, neoplastic or congenital causes. Most primary abdominal wall neoplasms are soft tissue tumours of mesenchymal origin and include soft tissue sarcomas, desmoid tumours and dermatofibrosarcoma protuberans. Overall, abdominal wall tumours are quite rare and the treatment is typically surgical resection regardless of histologic subtype.¹

Patients often present with late-stage disease, once the mass is palpable. If thought to be neoplastic, differential diagnosis is narrow and is most likely to involve desmoid tumours, metastases from other cancers or soft tissue sarcomas. While all of these abdominal wall tumours are rare, even more rare are the abdominal wall masses that are carcinomas.

In this case report, we present a series of patients with metastatic abdominal wall adenocarcinoma of unknown primary origin. Due to size and depth of invasion, these tumours required collaboration with other surgical services and involved significant preoperative planning for successful resection.

Case presentation

We present a case series of three patients with abdominal wall masses whom biopsy revealed adenocarcinoma without a site of primary disease identified.

Patient A

Patient A is a 49-year-old female patient with surgical history of three caesarean sections who presented to her primary care physician with a mass in her abdomen increasing in size. On evaluation, she had a right lower quadrant abdominal wall mass with minimal tenderness to palpation. It was firm and irregular in shape. A CT scan was then ordered, showing a mass measuring 7×11x6 cm (figure 1) involving the rectus musculature. Biopsy was performed showing poorly differentiated carcinoma. Staging CT chest/abdomen/pelvis showed no evidence of metastatic disease and no evidence of lymphadenopathy. Colonoscopy, mammogram and pelvic ultrasound were also negative. Tumour markers, including CEA, CA 19–9 and CA-125 were ordered and were within normal limits.

Figure 1.

Patient A’s abdominal wall mass measuring 7×11 x 6 cm and involving the rectus musculature (arrow).

At this time, the histopathology was indeteminate and workup had not concluded whether the mass was primary tumour or a metastatic tumour. Surgical resection was recommended for complete pathological assessment and treatment. Resection was coordinated with the plastic surgery team for reconstruction of the abdominal wall. She underwent resection of her infraumbilical abdominal wall, encompassing the entire thickness of the anterior abdominal wall and right rectus sheath. There was no intraperitoneal involvement or disease. The abdominal wall was closed with a bridging mesh for ventral hernia repair with an incisional wound vac in place.

Her postoperative course was complicated by postoperative ileus and wound dehiscence requiring complex closure. Final pathology showed clear cell carcinoma of Mullerian origin with angiolymphatic invasion and negative margins. We arranged follow-up with the gynaecologic oncology team, who recommended adjuvant chemotherapy, followed by total abdominal hysterectomy and bilateral salpingo-oopherectomy (TAH-BSO). She declined chemotherapy and will pursue TAH-BSO after she heals from her most recent wound closure.

Patient B

Patient B is a 55-year-old female patient with history of two caesarean sections and hysterectomy who presented with 3-month history of abdominal and groin pain. She was evaluated by her primary care physician, who ordered a CT scan, this revealed a mass measuring 4.5×5.4 cm in size encompassing the abdominal wall and rectus musculature (figure 2). She was then referred to our practice. On our initial examination, her abdomen was found to be nontender and nondistended with a palpable irregular mass at the midline. Tumour markers, including CEA, CA 19–9 and CA-125 were ordered and were within normal limits. Imaging was reviewed and staging CT scans were recommended. These were performed, all of which were negative for primary or metastatic neoplastic disease. Recent colonoscopy and mammogram were also negative. PET scan was also obtained showing hypermetabolic activity at the known abdominal wall mass site with nearby lymph node enhancement. Fine-needle aspiration was performed of the mass at this time, revealing poorly differentiated adenocarcinoma.

Figure 2.

Patient B’s abdominal wall tumour measuring 4.5×5.4 cm (arrow) identified on scan after presenting with abdominal pain.

Based on this information, surgical resection was recommended in collaboration with the plastic and reconstructive surgeons for reconstruction of the abdominal wall. We performed a complete resection of the tumour, which encompassed the right rectus muscle. The mass extended to the pubic symphysis distally, laterally to the anterior superior iliac spine on the right side, and included a portion of the left rectus muscle. Satellite nodules identified on PET scan as lymph nodes were resected en bloc. She was then closed in collaboration with Plastic Surgery team with a bridging mesh.

Her postoperative course was complicated by wound infection requiring excision of mesh with repeat operation for new mesh placement. The pathology revealed adenocarcinoma of Mullerian origin. She was then referred to the gynaecologic oncology team. Follow-up labs were significant for rising CA-125 and imaging 3 months after resection showed new pulmonary nodules and large inguinal node. These findings were concerning for metastatic disease and biopsy was performed of right inguinal node, revealing recurrent disease. She is currently undergoing chemotherapy with carboplatin and paclitaxel. The CA-125 is appropriately decreasing.

Patient C

Patient C is a 50-year-old female patient with history of caesarean section and tubal ligation who presented with sudden-onset of abdominal pain. At an outside hospital, she had imaging showing a mass that was initially identified as a rectal sheath haematoma measuring 14×6x9 cm in her abdominal wall which was subsequently drained. Pathology showed the drained fluid was positive for adenocarcinoma and she was then referred to our centre 3 months later. On evaluation at our institution, she was found to have a nonhealing wound on her abdominal wall with slight tenderness to palpation on examination. Palpable underlying mass was noted with no overlying erythema or fluctuance. CT scan at this point revealed an 18×8x12 cm mass (figure 3) encompassing the abdominal wall, which was significantly larger than prior imaging. We then recommended PET scan which showed a large, heterogeneous, hypermetabolic mass in the anterior abdominal wall with mesenteric lymph node enhancement. PET scan also showed hypermetabolic area of the uterine fundus. Staging CT scans were negative for metastatic disease. As a clear primary tumour source had not been identified, resection was recommended for treatment and diagnosis.

Figure 3.

Patient C was initially diagnosed as a rectus sheath haematoma (18.4x8.6x12.8 cm, arrow) and underwent drainage, which eventually revealed poorly differentiated carcinoma.

She was taken to the operating room in conjunction with the plastic surgery team for resection and complex abdominal wall reconstruction. A bridging mesh was placed for closure. Final pathology was significant for metastatic epithelioid trophoblastic tumour with negative margins. She was then referred to gynaecologic oncology. Per their recommendations, she additionally completed three cycles of EMA-EP (etoposide, cisplatin, methotrexate and dactinomycin) postoperatively, followed by an open TAH-BSO. Closure was performed by plastic surgery team concurrently. Pathology from the TAH-BSO was negative for malignancy and she is currently under surveillance with the gynaecologic oncology team.

Discussion

Cancers of unknown primary origin require through evaluation for site of primary disease and should include evaluation for common cancers as well as more rare tumours based on site of metastasis. Treatment is difficult because cancers of unknown primary are typically more aggressive with poor prognosis, 80% of all patients diagnosed have a median survival of 6 months.²

Ideally, according to current guidelines, the diagnostic process for a cancer of unknown primary origin begins with a complete history and physical examination including palpation of lymph node basins. Laboratory testing is commonly next, including tumour markers. Imaging is typically a CT or PET scan as well as a mammogram, colonoscopy, laryngoscopy/bronchoscopy and pelvis ultrasound based on lymph node findings on physical examination or imaging.²

However, as we noted in our cases, physical examination, labs, and imaging were not significant for a site of primary or metastatic disease. Therefore, tissue diagnosis with core needle biopsy is imperative so histological diagnosis can separate carcinoma from other more common causes, such as haematoma, lipoma, lymphoma, melanoma or sarcoma.² Our biopsies all were significant for poorly differentiated adenocarcinoma.

When adenocarcinoma of the abdominal wall is identified, complete staging should be performed and a search for the primary site of disease. This includes CT scans of chest, abdomen and pelvis as well as endoscopy, skin examination and mammogram to evaluate for primary site. Tumour markers can be useful, including CEA, CA-125, AFP, beta HCG and CA19-9 to assist with determining primary site. If only a single site of disease is identified, as in the cases presented here, surgical resection is recommended for treatment as well as establishment of a definite diagnosis. There is currently a paucity of data for neoadjuvant chemotherapy or radiation, but this should be considered if diagnosis can be made on needle biopsy. At this time, empiric adjuvant chemotherapy is acceptable in patients with poorly differentiated carcinoma.

Metastasis of gynaecologic origin presenting in the abdominal wall are extremely rare. More commonly, patients who have endometriosis can present with abdominal wall endometriosis. This is most often seen in patients who have a previous caesarean section and presents about 2–5 years after the caesarean section.³ There are also many cases of endometriomas and endometriosis as a result of amniocentesis or laparoscopic gynaecological procedures. Therefore, when evaluating a patient with abdominal wall mass clinicians should have sequelae of endometriosis as part of the differential, especially when the patient has a history of a gynaecological procedure.

On review of the literature, there have been only two other cases of epithelioid trophoblastic tumour at the site of a prior caesarean section incision site.⁴ These patients required multiple rounds of chemotherapy in addition to multiple resections for recurrence of disease, eventually resulting in a hysterectomy with BSO.^{4 5}

Clear cell carcinomas of the abdominal wall are also rare and have been described arising from malignant transformation of endometriotic implants in scars from prior gynaecological operations. There have been several case reports of this entity, and surgical resection was performed in all of the cases. The use of adjuvant radiation, chemotherapy or TAH with BSO is varied in these cases.⁶

As evidenced by the cases presented here, abdominal wall adenocarcinoma with unknown primary is a difficult case to treat as there is no current guideline for resection margins or for neoadjuvant/adjuvant chemotherapy and radiation. This is even more challenging as these tumours can have significant morbidity associated with them. All three cases had significant postoperative complications, mostly involving infection and wound dehiscence. It is also important to note that these cases all had pathology consistent with gynaecological origin in patients who had previous gynaecological operations, therefore, this should be part of the differential diagnoses in applicable patient populations. We recommend recruiting a multidisciplinary team to evaluate and treat these patients, as reconstruction and adjuvant therapy options are vital to a successful outcome.

Learning points.

• When evaluating a soft tissue mass in the abdomen that appears suspicious on examination or on imaging, neoplasm should be on the initial differential diagnosis. We recommend treating these masses as a cancer of unknown primary until imaging and/or biopsy prove otherwise.

• Current guidelines suggest that cancers of unknown origin must have a complete history, physical examination, PET or CT imaging for staging and tumour markers done. If only a single site of disease is identified without clear primary site, surgical resection is recommended.

• Cancer of unknown primary is challenging and there are no current guidelines for neoadjuvant or adjuvant chemotherapy and radiation in the setting of a surgical resection. Multidisciplinary team evaluation and management is imperative.

• In patients with surgical history of gynaecological operations and abdominal wall masses, tumours of gynaecological origin should be in the differential diagnosis.