Emphysematous gastritis after metastatic malignant melanoma: a radiological surprise

Abstract

Malignant melanoma is cancer of the skin which commonly metastasises to the stomach. There have been no reported cases of emphysematous gastritis secondary to metastasis of malignant melanomas, to date. However, a 61-year-old woman with metastatic malignant melanoma of the left great toe presented to us with symptoms of severe left hypochondrium pain associated with high-grade fever, gross abdominal distension and recurrent vomiting. Two months earlier, metastasis was observed to have spread to the stomach and inguinal lymph nodes. At this stage, the patient opted for traditional medication instead of definitive surgery and chemotherapy. Radiological imaging revealed an emphysematous change to the stomach which was radiologically consistent with gastric malignant melanoma. Unfortunately, the patient succumbed to this rare condition.

Background

According to global cancer statistics from 2018, melanoma of the skin has an incidence of 1.6% worldwide with an incidence of 0.23% in Malaysia.¹ Patients with malignant melanoma generally do poorly with a 5-year survival rate of only 15%.¹ The majority of patients with melanoma who present early in the disease eventually go on to develop metastases.² It has been reported that almost 20% of malignant melanoma mortalities have gastric metastases.³ Despite its supposedly common occurrence, there have been no reported cases of an emphysematous gastric change of a metastatic melanoma to date. Herein, we highlight the case of a 61-year-old woman with metastatic malignant melanoma of the left great toe and emphysematous changes to the stomach.

Case presentation

A 61-year-old woman with underlying type 2 diabetes mellitus presented with a discoloured left big toe for which no treatment had been sought in 15 years. She presented in December 2016 with left inguinal swelling and persistent blackish discolouration of the left big toe. Ray’s amputation was done on the left great toe and histopathology analysis showed evidence of malignant melanoma.

Investigations

Initial staging CT scan (figure 1) showed metastatic disease due to the enlarged inguinal lymph nodes. During clinic review it was noted that the left inguinal lymph node had become more enlarged with pus discharging from the wound. The core biopsy of the infected inguinal lymph node was consistent with metastasis of malignant melanoma. Consequently, the patient was given a course of chemotherapy intended as palliative care.

Figure 1.

Initial CT 2 months prior to acute presentation, which showed an eccentric gastric mass (arrow) in the greater curvature in sagittal (A) and coronal (B) view.

Post-chemotherapy staging CT scans showed an eccentric soft tissue attenuation in the greater curvature of the stomach associated with omental and peritoneal infiltration. Considering the histopathological results of both left great toe and left inguinal lymph node, gastric metastasis secondary to metastatic malignant melanoma was considered the most likely diagnosis. The patient then opted for traditional treatment and refused chemotherapy. She subsequently presented again 2 months later with severe left hypochondrium pain and gross abdominal distension. She had high-grade fever for 1 week, was unable to tolerate food or liquids, and endured recurrent bouts of vomiting. No episodes of haematemesis were claimed.

Repeat investigations were performed. The white cell count was observed to be high, measuring 36×10⁹/L with 65% neutrophils. An abdominal radiograph revealed the stomach to have a mottled appearance with extra-luminal air suggestive of pneumoperitoneum (figure 2). A contrast-enhanced CT scan of the abdomen and pelvis revealed a gas-filled eccentric stomach mass lining the greater curvature which was larger in comparison with the findings of the initial abdominal CT scan conducted 2 months earlier. This emphysematous mass was affecting the stomach lumen and causing partial gastric outlet obstruction (figure 3A, B). There was a small defect in the outer wall of the emphysematous mass, suggestive of a rupture and indicative of pneumoperitoneum (figure 3C).

Figure 2.

Erect chest radiograph during the acute presentation showed air under the diaphragm (arrow) overlying the mottled gastric mass, suggestive of pneumoperitoneum.

Figure 3.

(A) Axial CT abdomen during the acute presentation showed an emphysematous eccentric mass in the greater curvature of the stomach which is compressing on the stomach lumen (arrow). (B) Coronal CT abdomen showed an emphysematous eccentric mass in the greater curvature of the stomach which is compressing on the stomach lumen (arrow). (C) Presence of extraluminal free-air suggestive of pneumoperitoneum (arrow).

In view of the fact that the patient was in shock and haemodynamically unstable and due to the high risk of surgery, both the patient’s family members and the surgeon agreed on antibiotic treatment and rejected surgery. However, the patient succumbed to severe septic shock a week after admission.

Differential diagnosis

Any patient who presents with gastric emphysema during radiological imaging must be considered from the perspective of differential diagnoses. Gastric emphysema is referred to as benign intramural gas collection secondary to non-infectious process.⁴ It could occur through traumatic injury to the stomach from nasogastric tube insertion, gastric band erosion or as the result of a motor vehicle accident.⁴ Non-gastric causes, such as ruptured bullous emphysema, involve free air from an alveoli rupture dissecting the vascular sheaths surrounding the ruptured alveoli and gradually seeping into the gastric mucosa.⁵

Treatment

Considering that the patient was in shock and haemodynamically unstable and due to the high risk of surgery, both the patient’s family members and the surgeon agreed on a course of antibiotic treatment and refused the option of surgery.

Outcome and follow-up

The patient succumbed to severe septic shock a week after admission.

Discussion

Pneumatosis intestinalis, defined as the presence of air in the bowel wall, is increasingly common probably due to higher detection rates secondary to increased usage of CT.⁶ Conversely, intramural gastric gas is still a rare radiological finding. Common differential diagnoses of intramural gastric air include gastric emphysema and emphysematous gastritis.⁴ It is important to be able to distinguish between emphysematous gastritis and gastric empyema as the prognosis and management of both these diagnoses differ significantly.

Gastric emphysema is defined as gastric wall air without an underlying infection. This phenomenon is typically caused by the following: (1) gastric outlet obstruction secondary to increased intragastric pressure; (2) trauma due to vomiting or iatrogenic cause; and (3) ischaemia.⁵ Patients with gastric emphysema have an excellent prognosis.⁷ Emphysematous gastritis, on the other hand, is caused by infection of the stomach wall with causative gas forming microorganisms resulting in sepsis. Common gas forming micro-organisms which colonise on the stomach wall, isolated from blood cultures or gastric biopsies, include Streptococcus and Escherichia coli.⁸ Corrosive substances, alcohol, non-steroidal anti-inflammatory agents, recent abdominal surgery and gastric infarction are risk factors described in literature which predispose patients to emphysematous gastritis.⁹ Prognosis of emphysematous gastritis is grave with a fulminant course and a 5-year survival rate of only 15%.¹ Another large case study of 64 patients revealed a 75% mortality rate with nearly all patients requiring surgery.¹⁰ However, a more recent study has shown a significant reduction of mortality rates to almost 33% due to a shift from early surgical intervention towards early esophagogastroduodenoscopy and advanced supportive care in the management of emphysematous gastritis.¹¹ Non-surgical management for emphysematous gastritis involves enhanced supportive care comprises intravenous fluid resuscitation, vasopressors, nothing by mouth and most importantly broad spectrum antibiotics.^{11 12} This significantly changes the prognosis of patients with emphysematous gastritis.

Infection of a nidus of gastric metastasis from metastatic malignant melanoma is a rare occurrence as gastric metastasis is, on its own, a rare complication of cancer. Among the reported malignancies which could cause gastric metastasis, malignant melanoma has the highest incidence of 29.6%.¹³ Unfortunately for the subject of this case report, the clinical presentation was too late for an isolate of causative micro-organism to be determined. According to De Palma et al, gastric metastasis typically occurs in the middle or upper third of the stomach.¹⁴ In our case it presented earlier, in the middle extending to the lower third and involving the duodenum.

Due to the rarity of cases of emphysematous gastritis secondary to malignant melanoma metastasis to the stomach, there are no set criteria for surgical intervention. Although gastrointestinal metastasis secondary to malignant melanoma shows mortality relief post-surgery (as mentioned by Berger et al) in an acute setting with the patient suffering from a life-threatening infection, a trial of broad spectrum antibiotics would seem to be more appropriate, unless the patient is physically fit for operation.¹⁵ In fact, there has been at least one reported case of successful conservative antimicrobial treatment of emphysematous gastritis.¹⁶

In conclusion, emphysematous gastritis is a grave lethal condition which could be reversed with prompt and reliable definite diagnosis for advanced supportive care and early endoscopic therapy.

Learning points.

• Intramural gastric gas, a rare radiological finding, should not be ignored as emphysematous gastritis is highly fatal.

• The differentiation between gastric emphysema and emphysematous gastritis is paramount in determining a patient’s further management and prognosis.

• Broad spectrum antibiotics have proven effective in treating emphysematous gastritis.