Soft tissue metastasis in colorectal cancer: a case report

Abstract

Background

Soft tissue metastases of solid tumors are rare events, especially for colorectal cancers.

Case presentation

We report herein the case of a 65-year-old Arab woman with soft tissue metastases (left arm, right scapula, and right axillary masses) of a colorectal cancer 4 years after the initial surgery. The patient was treated with folinic acid–fluorouracil–irinotecan and bevacizumab as first-line treatment. One year after completion of chemotherapy, the patient remained alive.

Conclusions

The key aim in reporting this case is to raise awareness among oncologists regarding potential unusual metastasis locations of colon adenocarcinoma such as skin and skeletal muscle.

Introduction

Soft tissue metastases of solid neoplasms are rare [1]. Their prevalence in autopsy patients was about 0.03–5.6% [2]. These metastases are even more uncommon when the primary neoplasm is colorectal.

Colorectal cancer is the third most frequent cancer and the second cause of death related to cancer, accounting for 1.8 million new cases and more than 881,000 deaths in the world [3]. It is frequently associated with liver and lung metastases. Metastases to soft tissue and skin are rarely reported. Indeed, soft tissue metastases are found only in less than 1% of such patients [2]. Soft tissue metastases are rare, but it is important to keep in mind potential unusual metastasis locations of colon cancer such as skin and skeletal muscle.

We report herein the case of a 65-year-old woman with soft tissue metastases of a colorectal cancer. The case report was written according to CARE guidelines.

Case report

We report the case of a 65-year-old Arab woman with medical history of cardiac arrhythmia and gastroesophageal reflux disease who was operated in 2017 for stage II (T3N0M0) right-sided colon adenocarcinoma revealed by abdominal pain and bleeding. The histological examination showed no lymphatic, vascular, or perineural invasion. She was not eligible for adjuvant chemotherapy. At 2 years of follow-up, she presented with pulmonary relapse of her colorectal adenocarcinoma and was treated with upper-right lobectomy and 6 months of 5FU + oxaliplatin (FOLFOX) chemotherapy. Four years after the initial surgery, the patient reported the appearance of multiple masses. The examination showed an 8 × 7 cm² left arm mass, a 5-cm right scapula mass, and a 5-cm right axillary mass (Fig. 1). These masses were not associated with inflammatory cutaneous signs. Blood testing showed increased carbohydrate antigen 19-9 (CA19-9) (72.92) and carcinoembryonic antigen (CEA) (258.6). A computed tomography (CT) scan revealed multiple massively necrotic right axillary masses, the largest of which was about 50 × 36 mm², invading the subscapular muscle, as well as a right scapular mass of 42 × 36 mm² (Fig. 2). A biopsy was then performed. The pathological examination demonstrated a malignant cellular proliferation arranged in glands with tumor necrosis. The mitotic index was high (15 mitosis/10CFG) and Ki67 was about 50%. Immunohistological stains were negative for GATA3, hormone receptors, and CK7, and positive for CK20. These elements were consistent with a moderately differentiated carcinoma of colonic subtype (Fig. 3a–c).

Fig. 1.

a Left arm mass, b right scapula mass, and c right axillary mass

Fig. 2.

a Right axillary masses invading the subscapular muscle and b right scapular mass

Fig. 3.

a Moderately differentiated gland forming carcinoma (hematoxylin-eosin, 10×). b Cribriform glands filled with necrotic debris (dirty necrosis), nuclear atypia (hematoxylin and eosin, 20×). c Tumor cells are positive for CD20 with membranous and/ or cytoplasmic stain (immunohistochemistry, 20×)

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) revealed a hypermetabolic left biceps muscle mass with a hypometabolic center (SUV_max = 14.13), a hypermetabolic retro muscle mass of the left external obturator muscle (SUV_max = 12.41), and hypermetabolism of the right psoas muscle (SUV_max = 6.9). It also found increased uptake by a right adrenal mass (SUV_max = 14) (Fig. 4).

Fig. 4.

a, b Hypermetabolic left biceps and right axillary muscles mass

The tumor was revealed to be KRAS mutated (codon 146) without a BRAF mutation.

Surgical intervention was not possible owing to the extension of the masses. The patient started folinic acid–fluorouracil–irinotecan (FOLFIRI) with bevacizumab as first-line treatment. Treatment was continued for 12 months. A CT scan performed after 12 months of chemotherapy and bevacizumab showed regression of the disease according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. At 1 year after completion of chemotherapy, the patient was still alive. A timeline of the events is presented in Fig. 5.

Fig. 5.

Timeline of the events

Discussion

Skin metastases from solid neoplasms are rare. Despite the fact that soft tissue accounts for half of the human body mass, hematogenous metastases to skin are rare. Locoregional extension of a primary tumor to soft tissue is much more frequent than hematogenous soft tissue metastases. Soft tissue metastases (to the skin and skeleton) are found in about 0.8% of cases [4]. This instance of extensive metastases with involvement of the skin and/or muscles highlights the difficulties involved in treating advanced cancers. Although uncommon, skin metastases can be linked to a number of original cancer types such as adenocarcinomas.

One of the most frequent causes of soft tissue metastases is breast cancer. With a median of 1–2 years following diagnosis of skin involvement, survival varies greatly depending on the severity of the disease.

Although cutaneous metastases are uncommon in colorectal cancer, they can indicate advanced illness with dismal prognosis.

The overall staging of lung cancer correlates with the survival rates of non-small cell lung cancer, which may spread to the skin.

Several factors contribute to the low frequency of soft tissue metastases, including temperature, pH, and the low blood flow in soft tissues [5]. Lung and kidney cancers are more frequently involved with soft tissue metastasis [6].

Adenocarcinoma is the most frequent histological subtype to spread to soft tissues. It is followed by clear cell carcinoma and squamous cell carcinoma [6, 7]. They are often associated with advanced disease. Indeed, soft tissue metastasis of solid cancers has poor prognosis regardless of the primary neoplasm [6]. This could be explained by the fact that soft tissue metastasis generally appears at an advanced stage.

For colorectal cancer, the autopsy registry in Japan has shown an incidence of 0.028% of soft tissue metastases [1]. Locoregional extension of the primary tumor to soft tissue is far more frequent than distant metastases. It could spread to distant skeleton through the hematological or lymphatic system. The most common locations involved with soft tissue distant metastases are the back, the abdominal wall, and the shoulder [6]. Soft tissue metastases from adenocarcinoma may mimic a soft tissue sarcoma. Immunohistochemistry staining is useful for confirming the diagnosis of skin sarcoma [6]. The importance of this case report lies in the need for vigilance: in patients undergoing follow-up for colorectal cancer, any skin mass that appears may be metastasis.

The clinical presentation is nonspecific. Clinically, the lesions can range from a simple erythema, a skin swelling of variable size, to palpable mass. This could explain the diagnosis at an advanced stage and its low incidence. Skin and muscle examination should be performed carefully in patients with solid cancers in general and colorectal cancer in particular. In addition to the clinical manifestation of the primary neoplasm, patients often present an isolated tumefaction [8]. For diagnosis, magnetic resonance imaging (MRI) is the most suitable technique to differentiate soft tissue metastases from sarcomas [9]. CT scan is also effective for diagnosis and the definition of the locoregional and distant extension of the tumor [1, 10]. The prognosis of patients with soft tissue metastases from adenocarcinomas is poor. In patients with colorectal cancer, it is important to perform careful skin examination to detect the slightest abnormality. Any detected lesion, even apparently a benign one, should raise the possibility of metastasis in this particular context.

Pathological examination and immunohistological staining confirm the diagnosis. It is strongly advised to use needle aspiration for biopsy because of local dissemination [11]. Patients with skin metastases typically have poor prognosis. Once cutaneous involvement is identified, survival chances for many solid tumors decline drastically.

Overall survival depends on the initial malignancy and the response to treatment; this usually varies from a few months to several years. Patients with multiple organ involvement often receive a prognosis expressed in months.

Conclusion

We report herein a rare case of soft tissue metastases of colon adenocarcinoma with KRAS mutation in a 65-year-old Arab woman that occurred 4 years after curative surgery. This can only make oncologists aware of the potential unusual metastasis locations of colon adenocarcinoma such as skin. Any lesion detected on skin examination should raise the possibility of metastasis in this particular context. Doctors should always be alert and if in doubt proceed with additional investigations.

Author contributions

Yosr Zenzri: concept, design, definition of intellectual content, manuscript preparation, manuscript editing, manuscript review. Zahra Ghodhbani: concept, design, definition of intellectual content, literature search, manuscript preparation, manuscript review. Haythem Yacoub: concept, design, definition of intellectual content, manuscript preparation, manuscript review. Yoldez Houcine: design, manuscript review. Hajer Ben Mansour: design, manuscript review. Khedija Meddeb: design, manuscript review. Nadia Maamouri: design, manuscript review. Amel Mezlini: definition of intellectual content, manuscript review. Guarantor: Yosr Zenzri.

Funding

No funding was received.

Data availability

The data that support the findings of this study are available on request from the corresponding author (YZ). The data are not publicly available due to restrictions, e.g., their containing information that could compromise the privacy of research participants.

Declarations

Ethics approval and consent to participate

This study protocol was reviewed and approved by Salah Azaïez Ethics Committee. Written informed consent was obtained from the patient for publication of the details of their medical case and any accompanying images.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

The authors have no conflicts of interest to declare.