Clinicopathological and Molecular Characteristics of Atypical Pulmonary Sclerosing Pneumocytoma With Multiple Metastases

Background: Few patients with pulmonary sclerosing pneumocytoma (PSP) may suffer from recurrence and oligometastasis as it is a benign tumor or has a low malignancy potential. Herein, an in-depth study, based on an extremely rare PSP case with atypical features, was carried out to elaborate the potential mechanism underlying the rapid malignant progression. Methods: The clinicopathological data of this atypical PSP (AP) case were obtained. Formalin ‐ xed and paran ‐ embedded tissues from all the lesions of AP and ve classic PSP cases (as control) were used for whole-exome sequencing (WES) and immunohistochemistry. Results: A 23-year-old male showed a 6.5-cm pulmonary nodule in the right middle lobe (RML) and enlarged mediastinal lymph nodes (LNs). He underwent thoracoscopic RML lobectomy, systematic LNs dissection, and mediastinal lymphadenectomy. The metastases to the cervical LNs and liver were detected in a short period and then resected. Postoperative pathological examination conrmed the diagnosis of PSP in all the lesions, based on the typical histological characteristics and immunophenotypes. Furthermore, WES identied both AKT1 E17K somatic mutation and TP53 C176Y germline mutation in this AP case. The genomic evolution analysis showed different evolutionary branches in the metastatic tumors distinct from the primary lesion. Moreover, compared to the control group, the AP case showed high copy number variations (CNVs) and signicantly high copy number instability (CNI). Conclusions: We speculated that the atypical histopathological features and malignant behaviors may be due to the co-mutations of somatic AKT1 E17K and germline TP53 C176Y, combined with the high CNVs and CNI. together all mutation forms, in almost all the PSP samples was 96% (81/84 cases) [16]. These results demonstrated that AKT1 mutation is the hallmark of PSP, and internal tandem duplications and point mutations were the most common forms. Nevertheless, the rapid recurrence of PSP, followed by multiple LNs and organ metastases, has never been reported. Also, the molecular mechanism of the malignant progression is yet lacking. Based on the current atypical PSP case (AP), we aimed to elucidate this mechanism of malignant transformation of PSP through clinicopathological, WES, and IHC data. gross specimen histopathology, IHC, cases in this study with mutations on the PH domain of the AKT1 gene (Q79K, W80R, and R76_C77insWPNTFIIR) did not show any malignant progression. Moreover, more than 40 PSP cases have been reported with AKT1 E17K mutation [15, 16], malignant progression has been rarely reported. Taken together, these indicated that single E17K mutation on the PH domain of the AKT1 gene might not be sucient to initiate the malignant transformation of the tumor. A 17-year-old girl suffering from multiple nodules in the right lung lobe diagnosed as PSP with both AKT1 E17K and BRAF V600E mutations The other PSP case with diffusely scattered nodules in the right lung, harbored AKT1 E17K and other 14 somatic gene mutations indicated that the combination of AKT1 mutations with other oncogenes accelerate the malignant progression of benign PSPs. For the rst time, reported a TP53 C176Y germline mutation, a likely pathogenic mutation according to the ClinVar and 1000Genomes database, in this extremely aggressive PSP case. Which consistent with the positive expression of the P53 mutant protein in the IHC assay. Therefore, rapid malignant progression leading to multiple metastases of this PSP case might be partially attributed to the combination of somatic AKT1 E17K mutation and germline TP53 C176Y mutation. of TP53 gene 80% of patients with syndrome diverse spectrum childhood- and adult-onset malignancies 1 (NCOR1) is a transcriptional regulator bridging repressive chromatin-modifying enzymes with transcription factors As a putative tumor suppressor and independent prognostic factor, the NCOR1 mutations resulted in embryonic lethality [34] and cell type- and tissue-specic functions in multiple cells and organs [35–38]. The mutation of NCOR1 R190_E191delins*leads to the premature transcriptional termination, followed by loss of function, which might generate excessive transcription. RECQL is also known as RECQL1 or RECQ1, one of the members of human RECQ helicase family [39]. The RECQL helicases that unwind dsDNA are involved in several important cellular functions, including DNA repair, replication, recombination, and transcription The phenotypes observed in RECQL loss-function mouse and human cells suggested its role in the maintenance of genome integrity, chromosomal stability and in the non-homologous end-joining DNA repair [41–43]. Mutations of some human RECQ helicases cause different heritable cancer susceptibility syndromes, such as Werner syndrome and Bloom syndrome [44]. These results indicated a tumor-suppressor role for RECQL. We identied RECQL gene V41sfs*14 mutation in the liver metastasis lesion. This loss-of-function mutation might result in the premature transcription termination of RECQL and high CNI of the DNA genome.


Introduction
Pulmonary sclerosing pneumocytoma (PSP), formerly known as pulmonary sclerosing hemangioma, is a rare primary lung tumor initially described by Liebow et al, in 1956 as a tumor with prominent sclerosis and vascularization [1,2]. It mainly affects adults > 50 years of age, with a female to male ratio of 5:1 [3,4].
Immunohistochemistry (IHC) markers clari ed the epithelial origin of PSP and suggested that the condition originated from incompletely differentiated type II pneumocytes. Therefore, the term "pulmonary sclerosing hemangioma" was abandoned in the WHO 2016 classi cation for lung and pleura tumors, and PSP was adopted [2,5,6]. Although PSP has some clinical and imaging characteristics for differentiation from similar lesions, these are not speci c for diagnosis [7,8]. At present, the diagnosis of PSP still depends on surgical pathology. The primary pathological characteristics include the following: 1) The tumor is mainly composed of well-differentiated surface cuboidal epithelial cells and polygonal stromal cells. 6 2) Four common histological patterns can be seen, including papillary, solid, sclerotic, and hemorrhagic structures, or mainly composed of two patterns, which can co-exist in single tumor. 3) Immunohistochemically, the surface cells and stromal cells show differential expression. The stromal cells are diffusely positive for vimentin, TTF-1, and EMA, and always negative for CK, CK7, NapsinA, SP-B, and CEA, while the latter molecules are always positive in the surface cells. Occasionally, PSP may manifest as multiple lesions, recurrence, regional lymph node (LN), or single organ metastasis, but does not seem to affect the prognosis. Therefore, PSP is considered as a benign or a low-grade malignant potential primary lung tumor [9][10][11][12][13][14].
The molecular alterations in PSP have been investigated in a few studies. A large-scale study using whole-exome sequencing (WES) identi ed a high frequency of AKT1 point mutations (31/68, 46%) in PSP samples [15]. Recurrent internal tandem duplications in the AKT1 gene in 22/44 tumor samples (50%) indicated that it was mutually exclusive of the other forms of AKT1 mutations, including point mutations and short InDels (insertions and deletions). The AKT1 mutation rate, taken together all mutation forms, in almost all the PSP samples was 96% (81/84 cases) [16]. These results demonstrated that AKT1 mutation is the hallmark of PSP, and internal tandem duplications and point mutations were the most common forms.
Nevertheless, the rapid recurrence of PSP, followed by multiple LNs and organ metastases, has never been reported. Also, the molecular mechanism of the malignant progression is yet lacking. Based on the current atypical PSP case (AP), we aimed to elucidate this mechanism of malignant transformation of PSP through clinicopathological, WES, and IHC data.

Patients and samples
Formalin-xed and para n-embedded (FFPE) tissues from the AP case and 5 classic PSP cases were obtained from patients diagnosed with pathologically veri ed PSP from the Department of Pathology of Daping Hospital (Chongqing, China) from July 9, 2018 to July 22, 2019. AP was a 23-year-old male diagnosed as PSP. Samples from the primary and metastatic lesions were used for further analysis. The control group consisted of specimens from 5 female patients (mean age, 53 years; age range, 43-63 years). The clinical and pathological data of the patients were obtained from medical records. All patients provided informed written consent to allow publication of their clinical data. The present study was approved by The Clinical Ethics Committee of Daping Hospital, Army Medical University (Chongqing, China).
IHC and double-labelling IHC FFPE tissues were sliced into 4-µm-thick sections. The tissues were subsequently depara nized and pretreated with 1 mmol/L EDTA at pH 9.0 in a high-pressure cooker for 3 min and then treated with 3% H 2 O 2 for 10 min. Subsequently, washing was performed for 3 min three times using 0.01 M PBS at room temperature, and the slides were incubated with primary antibodies (Supplemental table 1) in the humidi ed chamber at 4˚C overnight. Next day, the slides were washed in 0.01M PBS and then incubated with goat anti-mouse/rabbit IgG ready-to-use reagent (PV-6000, ZSGB-BIO, China) at room temperature for 30 min and stained using 3,3'-diaminobenzidine for 5 min at room temperature. Double-labelling IHC: after the staining of 3,3'-diaminobenzidine (PR or TTF-1), the slides were washed using 0.01 M TBST for 3 min three times at room temperature, and incubated with antibody CK7 in the humidi ed chamber at 37˚C for 1 hour. The slides were washed in 0.01 M TBST and then incubated with alkaline phosphatase horse anti-mouse IgG reagent (1:50, ZB-2310, ZSGB-BIO, China) at room temperature for 30 min and stained using alkaline phosphatase substrate for 30 min at room temperature. The slides were reviewed using bright-eld microscope (BX41, Olympus. 40×) and Cell Sens Standard software (version 1.16, Olympus) by pathologists. DNA extraction, library preparation and WES analysis WES and bioinformatic analysis of tumor specimens were conducted at a CAP-certi ed laboratory (GeneCast Biotechnology Co., Beijing). For each patient, archived FFPE blocks of tumor biopsies were used for DNA extraction. Genomic DNA was extracted from FFPE sections using the BLACK PREP FFPE DNA kit (AnalytikJena) according to the manufacturer's protocol. The quantity and quality of the extracted DNA were evaluated using a Qubit 3.0 uorometer(Thermo Fisher Scienti c)and Bioanalyzer 2100 (Agilent Technologies). DNA was fragmented using a Covaris M220 sonication system (Covaris) to obtain 200 bp fragments and puri ed using Agencourt AMPure XP beads (Beckman Coulter). Library preparations of the fragmented DNA were performed using the KAPA Hyper Prep Kit (KAPA Biosystems), following the manufacturer's protocol. Libraries with different indices were pooled for Hypercap Target Enrichment Kit(Roche), and SeqCap EZ MedExome kit(Roche) covering the exome genes. The captured library was further ampli ed using Illumina p5 (5' AAT GATACG GCG ACC ACC GA 3') and p7 (5' CAA GCA GAAGAC GGC ATA CGA GAT 3') primers in the KAPA Hi -Hot Start Ready Mix (KAPA Biosystems), and puri ed with Agencourt AMPure XP beads. Sequencing libraries were quanti ed by Bioanalyzer 2100 (Agilent Technologies). The nal libraries were sequenced on an Illumina Novaseq 6000 platform to a mean coverage depth of at least 100×, following the manufacturer's instructions.

Statistics analyses
The bioinformatic pipeline for WES analysis attached as the supplemental data. Copy number variations (CNVs) calling was determined using CONTRA paired method [17]. The genome DNA copy number instability (CNI) was calculated by the method described before [18] and the results were considered statistically signi cant at a p value less than 0.05.LICHeE software was used for clonal evolution analysis based on the somatic mutations [19]. Venn diagram was drawn by the venn diagram package of R software [20].

Results
Clinical history AP presented non-productive cough, chest distress, and fever for one month. He had no smoking and family disease history. Chest enhanced computed tomography (CT) scans con rmed a 6.5-cm pulmonary nodule in the right middle lobe (RML), with enlarged mediastinal LN ( Fig. 1A Histopathologic ndings con rmed the diagnosis of PSP with multiple LNs and liver metastases A large solid mass was found in the RML. The single tumor was well-demarcated and circular, with grayish-white, slightly tough texture cut surface, measuring 6 cm in diameter ( Fig. 2A). Microscopically, the boundary between the tumor and the surrounding lung tissue was relatively clear except that a few minor in ltrative nodules were observed outside the main body of the tumor (Fig. 2B). Solid cell area, papillary structure and sclerotic area composed of different proportion of surface epithelioid cells and polygonal stromal cells constitute the common mixed growth pattern of PSP (Fig. 2C).The papillary structures in sclerosing background (Fig. 2E), as well as the transition zone of solid and papillary pattern (Fig. 2D),were shown, respectively. Focally in solid cell area, polygonal tumor cells are diffusely arranged, the cell density is increased, and some pleomorphism and atypia appear, but the mitosis is di cult to nd ( Fig. 2F and G). Focal tumor necrosis was noticed (Fig. 2H). Tumor thrombus was found in some blood vessels in the peripheral region of the tumor (Fig. 2P, box). IHC revealed that both the stromal cells and cuboidal surface cells were diffuse positive for EMA and TTF-1 (Fig. 2J), whereas only the surface cells expressed CK (Fig. 2I), CEA, and NapsinA (Fig. 2K). Double-labelling IHC (Fig. 2L and M) showed CK7 and TTF-1 positive, PR negative in surface-lining cells; whereas CK7 negative, TTF-1 and PR positive in stromal cells. Most of the tumor cells were p53-positive (indicating TP53 mutation, Fig. 2N), whereas only a few cells expressed CD56, Syn, and ER. Immunostaining for S-100, actin, desmin, HMB45, p63 and TFE3 were negative. The Ki-67 labeling index (LI) was about 5% (Fig. 2O). ERG staining outlined the blood vessels and set off the tumor thrombus in vessels (Fig. 2P). The IHC results of 5 classic PSP cases as control were consistent with those of AP except that p53 was negative and Ki-67 LI was 0-2%.
The histopathological and IHC examination of the resected specimens con rmed multiple organ metastasis of hilar, mediastinum ( Fig. 3A-E), cervical LNs, and liver ( Fig. 3F-J). Strikingly, the normal structures of LNs and the liver were partially destroyed. The polygonal tumor cells showed diffuse or patchy in ltration, increased pleomorphism and atypia, with intranuclear inclusions and tumor giant cells. Interstitial vascular hyperplasia and focal necrosis were easily identi ed. The immuno-phenotypes of the tumor cells were similar to that of stromal cells of the primary lung tumor: diffuse expression of EMA, TTF-1 ( Fig. 3C and H), PR ( Fig. 3D and I) and p53 (Fig. 3J), but no expression of CK7 and NapsinA (Fig. 3C, red box). The Ki-67 LI of mediastinum LNs and liver metastasis was higher than that of the primary lesion (25% vs 5%) (Fig. 3E).
Identi cation of oncogenic mutations of AKT1 and TP53 in the AP Herein, we conducted a comprehensive examination of genetic alterations (somatic mutations) in FFPE samples from 6 cases of PSP using WES: 4 samples from the primary and three metastatic lesions of AP with matched adjacent normal tissue and 5 samples from the classic PSP cases in the control group. A high frequency of AKT1 E17K mutations was detected in primary lung tumor, mediastinal LN, cervical LN, and liver metastatic lesions of AP (16.14%, 16.83%, 34.51%, and 21.88%, respectively). AKT1 gene mutations were detected in 3/5 classic PSP cases, including missense mutations (W80R + Q79K) in 2 cases and an internal tandem duplication (R76_C77insWPNTFIIR) in 1 case. Wild-type AKT1 genes were identi ed from the other two classic PSP cases (Fig. 4A, Table 1). TP53 C176Y mutations were identi ed in the primary lung lesion, mediastinal LN, cervical LN, and liver metastatic samples of AP, with the frequency 42.41%, 68.63%, 72.84%, and 50.52% respectively. Interestingly, TP53 C176Y mutations were also detected in the paired normal tissue adjacent to the primary lung tumor (frequency 33.02%), suggesting that TP53 C176Y was a germline mutation in this metastatic PSP patient (Fig. 4A, Table 1). This phenotype was further con rmed by the identi cation of the same mutation in the peripheral blood mononuclear cell (PBMC) sample (Supplemental Fig. 1).

Genomic evolution analysis and copy number instability of AP
In order to demonstrate the malignant progression of this case, we analyzed the mutation evolution differences between the primary foci and three metastatic lesions based on the data of WES. These foci and lesions carried three "trunk mutations": AKT1 E17K, NCOR1 R190_E191delins*, and COL2A1 P1183H. Along with disease progression, the three metastatic lesions evolved anLRP1B W1304C mutation, which was the main difference from the primary tumor.
Based on the WES data, genomic DNA copy number variation (CNV) analysis was performed on four lesions of AP and 5 samples of the control group. A higher number of CNVs were detected in the AP samples than the control group. Genes with high abundance of CNVs in the samples of AP included SP8, MIB2, LOC101927859, FAM230A, and ACAP3. Also, differences were noted among the four lesions of AP: the mediastinal LN (AP1832384), cervical LN (AP1905401), and hepatic metastatic lesion (AP1909075) harbored a higher number of CNVs than the primary tumor (AP1820610) (Fig. 4E). In addition, a signi cantly higher copy number instability (CNI) was observed in the AP samples than the control group (P = 0.02) (Fig. 4F). The tumor mutational burden was 2.3 Muts/Mb (TMB-L) calculated based on the WES data.

Clinical outcome after the fourth operation
Due to the high level of serum prolactin with positive estrogen receptor (ER) and progesterone receptor (PR) in operative FFPE tissues as assessed by IHC, the patient received antiestrogen therapy with medroxyprogesterone after the operation. In May 2019, chest and abdominal enhanced CT scans showed dramatic progression: multiple nodules in the right lung and multiple enlarged LNs in neck, jaw and right supraclavicular fossa. Since the antiestrogen therapy was ineffective, the patient stopped taking medroxyprogesterone orally.
In September 2019, the patient felt that the neck mass was signi cantly larger than before. Chest and abdominal enhanced CT scans (Fig. 5A-D) showed an enlarged mass in both lung hilum (5.8cm × 5.4 cm) and right supraclavicular fossa (5.7 cm in maximum dimension), multiple nodules in the liver and left kidney, and thoracic 8th and11th vertebral osteolytic bone destruction. The patient was administered pembrolizumab treatment at 2 mg/kg intravenously every 3 weeks, combined with apatinib at 250 mg/day orally since October 2, 2019. After 2 cycles of combination therapy, the patient reported feeling well, and the neck mass was signi cantly reduced.
On November 11, 2019, chest enhanced CT showed a signi cant shrinkage in the volume of multiple lesions including right supraclavicular fossa, hilum, mediastinum, and liver ( Fig. 5E-H). The patient subsequently received another three cycles of the same treatment, achieving a partial response.

Discussion
Due to the lack of speci city in clinical and imaging features, the diagnosis of PSP mainly depends on postoperative pathological examination. The diagnosis of typical PSP, characterized by two different cell components, four typical histological types, and immunophenotypes with speci c features, was not di cult for pathologists [6]. However, some atypical cases showed either different clinical behaviors from typical PSP, such as recurrence or metastasis, or confused histological characteristics, such as limited typical patterns, cytological atypia, and focal necrosis. These atypical cases could be misdiagnosed as papillary or solid subtype of lung adenocarcinoma and neuroendocrine tumor, especially in the case of needle biopsy or intraoperative frozen diagnosis [21]. In this case, the delayed diagnosis at biopsy was mainly attributed to the atypical phenomenon, including multiple LN metastases, papillary and solid growth pattern, cellular atypia, tumoral necroticfoci, and higher Ki-67 LI than that of ordinary PSP cases. Therefore, for accurate conclusions, we should comprehensively analyze the results of imaging, gross specimen performance, histopathology, IHC, and molecular detection, if necessary.
There are several points worth emphasizing on the pathological diagnosis. Firstly, PSP usually presents as an isolated, solid, and well-de ned mass, which is different from the general changes of invasive adenocarcinoma. Secondly, we should deduce the basic structure for the diagnosis of PSP by observing the sections carefully and comprehensively: the papillary growth pattern and its diffuse distribution of interstitial cell components, as well as other histological patterns, such as solid cell area, intra-alveolar hemorrhage, and sclerotic changes. Thirdly, although there is no speci c single antibody for diagnosis, establishing the diagnosis by the appropriate combination of antibodies and observing the obvious difference of immunophenotype between epithelioid cells and stromal cells is imperative. Finally, for the atypical cases, the molecular pathologic nding is helpful for differential diagnosis. As in this case, we identi ed the AKT1 E17K point mutation through WES analysis, which is considered to be a relatively speci c molecular feature of PSP [15,16], but no other common driving gene mutations related to lung cancer were found, which plays an important role in strengthening our con dence in the diagnosis of this atypical disease.
PSPs were mostly diagnosed in female patients (83.34%), aged 38-61 years [22]. The malignant progression and metastasis of PSP were extremely rare. The reported PSP patients with LN [9,13,14,23] or organ metastases [11,24] were mostly females, and only one male patient suffered from mediastinal LN metastasis [25]. Herein, we reported an extremely atypical case: a young male patient suffering from an aggressive PSP with multiple LN and organ metastases during 7 months after the resection of the primary lung lesion.
AKT1 E17K mutation, identi ed from all primary and metastatic lesions in this study, were localized to the pleckstrinhomology domain (PH domain), which is crucial for membrane localization and downstream activation of AKT1 [26]and is known to promote growth factor-independent cell proliferation [27,28]. However, 3 PSP cases in this study with mutations on the PH domain of the AKT1 gene (Q79K, W80R, and R76_C77insWPNTFIIR) did not show any malignant progression. Moreover, though more than 40 PSP cases have been reported with AKT1 E17K mutation [15,16], malignant progression has been rarely reported. Taken together, these results indicated that single E17K mutation on the PH domain of the AKT1 gene might not be su cient to initiate the malignant transformation of the tumor. A 17-year-old girl suffering from multiple nodules in the right lung lobe diagnosed as PSP with both AKT1 E17K and BRAF V600E mutations [29]. The other PSP case with diffusely scattered nodules in the right lung, harbored AKT1 E17K and other 14 somatic gene mutations [30]. These indicated that the combination of AKT1 mutations with other oncogenes might accelerate the malignant progression of benign PSPs. For the rst time, we reported a TP53 C176Y germline mutation, a likely pathogenic mutation according to the ClinVar and 1000Genomes database, in this extremely aggressive PSP case. Which consistent with the positive expression of the P53 mutant protein in the IHC assay. Therefore, rapid malignant progression leading to multiple metastases of this PSP case might be partially attributed to the combination of somatic AKT1 E17K mutation and germline TP53 C176Y mutation. Germline mutations of TP53 gene have been identi ed in 80% of patients with Li-Fraumeni syndrome (LFS), a cancer predisposition syndrome associated with high risks for a diverse spectrum of childhood-and adult-onset malignancies [31]. However, neither rst-nor second-degree relatives had been diagnosed with any cancer or sarcoma, this patient does not meet the classic LFS diagnosis criteria [32].
Evolutionary analysis revealed distinct molecular biological variations at different malignant progression stages of this case. Among these molecular variations, NCOR1 R190_E191delins* and RECQL V41sfs*14 might be the two additional important mutations that are responsible for malignancy. Nuclear receptor co-repressor 1 (NCOR1) is a transcriptional regulator bridging repressive chromatin-modifying enzymes with transcription factors [33]. As a putative tumor suppressor and independent prognostic factor, the NCOR1 mutations resulted in embryonic lethality [34] and cell type-and tissue-speci c functions in multiple cells and organs [35][36][37][38]. The mutation of NCOR1 R190_E191delins*leads to the premature transcriptional termination, followed by loss of function, which might generate excessive transcription. RECQL is also known as RECQL1 or RECQ1, one of the members of human RECQ helicase family [39]. The RECQL helicases that unwind dsDNA are involved in several important cellular functions, including DNA repair, replication, recombination, and transcription [40]. The phenotypes observed in RECQL loss-function mouse and human cells suggested its role in the maintenance of genome integrity, chromosomal stability and in the non-homologous end-joining DNA repair [41][42][43]. Mutations of some human RECQ helicases cause different heritable cancer susceptibility syndromes, such as Werner syndrome and Bloom syndrome [44]. These results indicated a tumor-suppressor role for RECQL. We identi ed RECQL gene V41sfs*14 mutation in the liver metastasis lesion. This loss-of-function mutation might result in the premature transcription termination of RECQL and high CNVs constitute a major source of variations among humans, underlying human evolution, many mental illnesses, developmental disorders, and cancers [45]. CNVs for NSCLC distinguished lung cancer from normal lung tissues, can be a prognostic indicator [46]. A number of low-to-common frequency CNVs might in uence the risk of epithelial ovarian cancer and tumor-gene expression [47]. DNA copy number losses in basal-like breast cancers were associated with signi cantly increased genomic instability and poor patient survival [48]. Herein, a higher number of CNVs were identi ed in the AP samples as compared to the control group and in metastatic lesions than the primary tumor of AP. Furthermore, the CNI was signi cantly higher in the AP samples than the control group. These factors could be ascribed to the rapid malignant progression of this PSP case. Although statistical bias may exist due to the limited number of cases, such signi cant differences in CNI values between different groups of the same disease are rather uncommon.

Conclusion
We reported an extremely rare case of PSP, which showed obvious atypical features in histopathology and malignant biological behaviors, such as rapid recurrence and multiple metastases. Based on the results of WES, we speculated that the somatic AKT1 E17K and germline TP53 C176Y mutations, combined with high CNVs and CNI might account for this malignant progression.