Introduction

Solid pseudopapillary tumour of the pancreas, designed by the World Health Organisation in 1996, was first described as papillary tumour of the pancreas—benign or malignant (Frantz’s tumour) [1]. Various other names have been used including papillary cystic tumours of the pancreas, papillary epithelial neoplasms, solid and papillary epithelial neoplasms and solid and cystic acinar cell tumours. Solid pseudopapillary pancreatic tumours (SPTs) account for <2% of exocrine pancreatic tumours which are found predominantly in women between 20–30 years. The aetiology is unknown and 85% are benign [2].

Malignant mesothelioma is rare but the incidence is rising. It is more common in men with incidence of 30 per million per years as compared to a female incidence of two per million per year [6]. The disease usually occurs between 50–70 years and is associated with asbestos exposure in 85–90%. We present the first case report of a patient presenting with SPT and malignant mesothelioma (MM) concurrently and the diagnostic dilemma.

Case Report

A 59-year-old carpenter with previous asbestos exposure presented with dyspnoea, unproductive cough and pleuritic chest pain. A chest radiograph (CXR) demonstrated pleural effusion and consolidation and the patient improved with treatment of his presumed pneumonia. His symptoms recurred and an incidental upper abdominal mass was detected. A computerised tomogram (CT) revealed a 13-cm pancreatic body tumour with areas of necrosis and calcification (Fig. 1a). Pleural malignancy was ruled out by pleural aspirate and biopsy. A distal pancreatectomy, splenectomy and partial colectomy were performed for the adherent tumour to the transverse colon. This was a tumour with histological and immunohistochemical (IHC) characters of SPT, a solid tumour of polygonal neoplastic cells around fibrovascular cores with cystic and pseudopapillary, and was positive for cluster differentiation (CD) 56 and β-catenin (Fig. 1c). There were frequent mitotic figures and vascular and adipose invasion suggestive of a tumour of malignant potential. Due to persistent respiratory symptoms, a further pleural biopsy was performed demonstrating malignant cells with a papillary pattern (Fig. 2b). This was thought to be metastases from the SPT but IHC staining for cytokeratin (CK) 5/6 and calretinin confirmed MM of the epithelial cell type. The patient developed multiple liver metastases 10 months after his operation. A biopsy showed polygonal malignant cells, around fibrovascular cores, positive for CD56 confirming metastases from the SPT. The patient died 2 years after presentation from metastatic disease.

Fig. 1
figure 1

a An abdominal CT showing the 13-cm solid pseudopapillary tumour of the body of the pancreas with areas of calcification (arrow up) and necrosis (arrow left). b The SPT of the body of the pancreas was fixed to the transverse colon. A distal pancreatectomy, segmental colectomy and splenectomy was performed. c Histology of the tumour of the pancreas demonstrated a well encapsulated tumour made up of polygonal malignant cells, positive for CD56 and β-catenin, with relatively frequent mitotic figures and vascular and adipose invasion (CD56, ×400)

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Fig. 2
figure 2

a A thoracic CT demonstrated a left-sided loculated pleural effusion, pleural thickening and collapse. b The pleural biopsy demonstrated malignant mesothelioma of epithelial type which was positive for cytokeratin 5/6 (CK5/6, ×400)

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Discussion

SPTs account for 1–2% of all exocrine pancreatic tumours; 90% are found in female between 20–30 years [2, 3]. The aetiology and origins are unknown. Only ∼15% of SPTs metastasise to the liver, peritoneum, omentum, lymph nodes and sub-cutaneous tissue [4]. Surgical resection can cure most SPTs. These tumours are usually found incidentally. The patients could present with abdominal mass or pain, as acute pancreatitis and phaeochromocytoma [3]. Abdominal radiograph and CT may demonstrate masses with calcification and solid and cystic areas. Magnetic resonance imaging, angiography and endoscopic retrograde cholangiopancreaticogram could be helpful. The tumours generally occur in the pancreatic body or tail and averages 8–10 cm. Macroscopically, the tumours are usually encapsulated with solid areas admixed with haemorrhagic and necrotic areas and cystic spaces [2]. Microscopically, there are pseudopapillary areas amongst haemorrhagic and pseudocytic structures. The tissue shows a micro-vasculature that forms pseudorosettes associated with hyalinised or myxoid stroma. The cells contains either eosinophilic or foamy cytoplasm and a hybrid immunophenotype combining mesenchymal, endocrine and epithelial differentiation [5]. Vimentin, CD5, β-catenin, neuron specific enolase, α1-antitrypsin, α1-antichymotrypsin and progesterone receptors are present in >90%, CK in 70% and synaptophysin in 22% of the tumours [5]. Malignant histological features include vascular and perineural invasion and local infiltration, nuclear atypia, high mitotic count and aneuploidy [4].

MMs are rare but more common in men and is associated with asbestos exposure in 85–90% of the patients with a latency of 25–40 years [6]. Other risk factors include simian virus exposure, radiotherapy, chronic pleural inflammation and chemical carcinogens [7]. MM can develop in the pleural (90–95%), peritoneum (5–10%), pericardium and the genital tract [7]. They start as nodules which coalesce to form solid tumours and encase the lungs and obliterate the pleural cavity. Pain, dyspnoea and constitutional symptoms are common. Eighty percent to 95% of patients develop pleural effusion. These tumours invade locally or metastasise to the hilar lymph nodes and any organs. CXR, thoracic CT or MRI may demonstrate pleural thickening, plaques, mass and effusion. Diagnosis may be difficult as only ∼30% and ∼75% of the cytology or biopsy is positive, respectively, but the yield is increased by video assisted thoracoscopy [8]. MM stains for calretinin (85%), vimentin (58%) and CK5/6 and 7 [9]. Electron microscopy often provides the diagnosis. The median survival is 4–18 months [10]. There are three histological types: epithelial (50%), sarcomatous (16%) or mixed (34%) [7]. The epithelial sub-type shows papillary, solid, tubular or vacuolated patterns. The sarcomatous form is made up of spindle- or ovoid-shaped cells [9]. This tumour is treated by a combination of surgery, chemotherapy, radiotherapy and immunotherapy.

From the initial presentation, there were difficulties in establishing the diagnoses in this patient. Firstly, the diagnosis of MM was delayed. A laparotomy would have avoided if MM was ascertained from the outset as the SPT was asymptomatic and would have been managed expectantly. The index of suspicion of MM should have been high as this 59-year-old man was exposed to asbestos. In addition, earlier repeated biopsies should have been performed as it is recognised that both the cytological and biopsy were of low diagnostic yields of only ∼30% and ∼75% [8], respectively. Secondly, the papillary histological feature demonstrated from the second pleural biopsy resulted in an initial diagnosis of metastatic disease from the SPT. The definitive diagnosis of MM was only established with the help of IHC, and the tumour was negative for CD56 and β-catenin [5] but positive of CK5/6 and calretinin [9]. Thirdly, the origin of the liver metastases was again only established with the help of IHC, with these secondaries being positive for CD56 and β-catenin [7]. This case report demonstrated that the diagnosis of rare tumours can be complicated and every aspect, from clinical presentation, signs and symptoms, imaging to pathological features should be taken into consideration. All the diagnostic dilemma was clarify by pathology, especially IHC, in this instance. Correct diagnoses were important in managing patients appropriately. This is the first reported case in which two extremely rare tumours developed concurrently in one patient. Although the aetiology of SPTs is unknown, it may be associated with factors which predispose patients to developing MM [7].