‘Microcystic pattern’ should be recognised as part of the morphological spectrum of solid‐pseudopapillary neoplasm of the pancreas

Abstract

Aim Solid pseudopapillary neoplasm (SPN) is an uncommon pancreatic tumour characterised by solid and pseudopapillary growth patterns. We have observed SPNs can show a microcystic pattern (microcystic SPN), which has been poorly described and may be confused with microcystic neoplasms. We conducted the present study to clarify the clinicopathological and immunohistochemical features of microcystic SPNs. Methods and results We examined a consecutive series of 44 SPNs and 10 serous cystadenomas (SCAs), and classified them into 13 microcystic SPNs (29.5%) and 31 conventional SPNs (70.5%). Clinicopathological analysis, immunohistochemical staining and mucin histochemistry were performed. Clear cell change, hyalinised stroma and haemorrhage were observed significantly more frequently in the microcystic SPNs compared to the conventional SPNs. Immunohistochemically, the microcystic SPNs showed significantly lower frequencies of CD10 (0%) and CD56 expression (62%) compared to the conventional SPNs (87%; P < 0.001, 90%; P < 0.0085, respectively). There were no significant differences in other clinicopathological and immunohistochemical features between the two groups (i.e. the nuclear expression of β‐catenin, E‐cadherin, progesterone receptor (PgR), lack of forkhead box (Fox)L2 and occasional oestrogen receptor (ER), AE1/AE3 expression). Microcystic SCAs lack such a characteristic immunophenotype. The myxoid stroma of microcystic SPNs contained hyaluronan revealed by Alcian blue stain with hyaluronidase digestion. Conclusion We thus conclude that the microcystic pattern should be recognised as a part of the morphological spectrum of SPNs. Our findings may contribute to the correct diagnosis of the pancreatic neoplasms with the microcystic pattern. In addition, we speculate that stromal change caused by an accumulation of hyaluronan may contribute to the microcystic pattern of SPN.

Clinical manifestations and multi-slice computed tomography characteristics of solid pseudopapillary neoplasms of the pancreas between males and females

“…In addition, percentage of solid tumors was higher, while percentages of hemorrhagic and cystic changes were lower in the male group than in the female group, which was in agreement with the findings reported by Lam et al [7]. Zou et al [14] found that collagen tend to be the main component of tumor stroma in SPNP males,while hyaluronan (HA) composed a considerable proportion in females, which was consistent with the conventional characteristics of SPNP [16]. McCarthy et al [17] reported that HA in stroma could promote tumor cell proliferation,which may explain the growth pattern and the degenetive changes in females in our study.…”

Clinicopathological and immunohistochemical study of 29 cases of solid-pseudopapillary neoplasms of the pancreas in patients under 20 years of age along with detailed review of literature

“…A study demonstrated microcystic pattern in almost 30% SPNs (microcystic SPNs) which may lead to confusion with microcystic pancreatic neoplasms. The study found that clear cell change, hyalinized stroma and hemorrhage were significantly more common in microcystic than conventional SPNs and that microcystic SPNs were much less likely to express IHC markers CD10 and CD56 [29]. We observed microcystic pattern in 24.1% of our cases (Table 1).…”

“…It is clear from the above discussion that practically all SPNs are positive for vimentin, beta catenin, cyclin D-1, alpha-1 antitrypsin and CD56 and are typically negative for E-cadherin [5,10,29,33,39]. PR negativity in SPNs is associated with worse prognosis.…”

Synchronous solid pseudopapillary neoplasm and invasive ductal carcinoma of the pancreas: a case report

“…However, 10–15% of SPN cases have aggressive features, including lymphovascular invasion, adjacent organ invasion, and metastatic disease [ 6 , 7 ]. Typical immunohistochemistry findings for SPN include positive staining for nuclear β-catenin and CD-10 [ 2 , 8 ]. Characteristic imaging features of SPNs include a calcified peripheral rim.…”