Pleuropulmonary blastoma type I presenting as a tension pneumothorax: a case report and review of the literature

Abstract

Pleuropulmonary blastoma (PPB) is a very rare, aggressive, embryonal pulmonary malignancy that mostly affects children under the age of 5 years. According to the histological features, three subtypes of PPB have been recognized: type I (purely cystic), type II (grossly visible cystic and solid elements), and type III (purely solid). The authors report a case of a 10-month-old male infant with type I PPB, who was clinically misdiagnosed with pneumothorax, that he presented complaining of shortening of breath, fever, and cough. Radiographs of the patient showed right pneumothorax, so he had managed accordingly in another centre without improvement. Then Computed Tomography showed a huge right upper lobe sepated pneumocyst, which was treated surgically and the diagnosis was confirmed by combining the imaging and the histopathological examination as PPB type I. PPB is a relatively rare tumour, and it is important to put PPB with their subtypes within the differential diagnoses of any pulmonary lesion in children below the age of 5 or 6 years, as the early diagnosis will help to give early management. Hence, the patient may have a better outcome.

Introduction

Highlights

• Pleuropulmonary blastoma (PPB) is a rare aggressive malignant tumour of childhood and must be one of the differential diagnosis of paediatric thoracic masses.

• PPB have wide variety of clinical pictures, diagnosis must be confirmed by pathological testing.

• Treatment of choice for PPB is surgical excision, and postoperative adjuvant chemotherapy or radiotherapy in some cases.

Primary pulmonary neoplasms are uncommon in children, one of the rare tumours is PPB, which is a malignant, aggressive, and dysontogenetic tumour, that originates from the lungs or pleura1. According to WHO classification, PPB is a soft tissue tumour of the lung that is distinct from that of other pulmonary blastomas2. PPB is of three types: type I or purely cystic, type II or cystic/solid, and type III or purely solid.

The incidence of PPB in children is ~0.5–1% of all primary malignancies of the lung3,4, occurs in children below the age of 6 years, with no clear gender preference2. To date, only a few articles of PPB have been described in the current English literature.

In this article, we describe a rare case of PPB type I in a 10-month-old infant, who was treated in our hospital and presented with nonspecific respiratory symptoms. Computed tomography (CT) scan demonstrated a huge right upper lobe sepated pneumocyst, compressing the left lung. The patient was treated with complete resection of the tumour. As the first case that was reported in Palestine as a case of PPB1, and the early correct diagnosis of our medical team helped in developing the treatment plan in a timely manner, and this in turn draws attention to put PPB in the differential diagnosis of lung lesions. More details and histological features will be discussed below compared to the previously published literature.

This case presentation has been reported in line with SCARE criteria5, which is used by authors, journal editors, and reviewers to increase the robustness and transparency in reporting surgical cases5.

Case presentation

A 10-month-old male infant with no significant antenatal history, was referred to our hospital for 1 week history of worsening cough associated with fever, hemoptysis, diarrhoea, vomiting, and worsening shortness of breath despite the management with IV antibiotics and corticosteroid in the hospital he was referred from. The patient is not on any regular medications, and his family history is negative for genetic or hereditary diseases. his past medical history was significant that he was admitted at age of 2 months to another hospital for hemoptysis and hematemesis, he was diagnosed as a lower respiratory tract infection and he was managed conservatively.

The patient was transferred to our institute by an ICU ambulance. He was placed on a mechanical ventilation prior to transfer electively due to worsening respiratory condition. He arrived to our hospital intubated and sedated on morphine and midazolam and appeared dyspnoeic, tachypneic and respiratory distressed. The report from the previous hospital highlighted that they are referring him as a case of persistent pneumothorax, the diagnosis of right pneumothorax was made by a chest X-ray (Fig. 1), and despite the insertion of a chest tube, there were no improvement, so chest CT scan was performed and showed a huge right upper lobe sepated pneumocyst, compressing the left lung, with mediastinal shift to the left and insignificant pneumothorax. Consequently, he was referred to our hospital for surgical intervention. On recent examination, he looked ill, bilateral wheezes were heard in chest auscultation, in addition to decreased air entry to the right chest especially to the peripheral middle and upper areas, with good entry to the left. His blood pressure was 92/55 mmHg, heart rate 125 beats per min, and respiratory rate 30 breaths per min. Arterial blood gases were performed and were within normal ranges. Laboratory investigations were also performed and shown in (Table 1).

Figure 1.

(A) Chest X-ray, AP view, prior to the surgery, showed huge cystic changes in the right lung, with mediastinal deviation to the left. (B) Chest X-ray, AP view, immediate postoperatively, the lung is fully expanded, a chest tube is in place, Note the thymus shadow. (C) Chest X-ray, AP view, postoperative day 4, After chest tube removal, the lung is fully expanded with no pleural effusion or pneumothorax. (D) Chest CT scan, axial section, done in the primary hospital before referral, showing huge sepated cyst in the right lung and minimal pneumothorax anteriorly. AP indicates AP Antero-Posterior; CT, computed tomography.

Table 1.

Showing laboratory test results preoperatively, postoperative day 1, and postoperative day 2

Laboratory test	Preoperative results	Postoperative day 1 results	Postoperative day 2 results	Normal ranges
CBC
WBC	8.53	6.043	8.563	(5.0–10.0) × 103
RBC	5.43	4.754	4.967	(4.6–6.2) × 103
HB%	11.9	10.13	10.26
HCT	37.1	33.1	34.65	40–52%
MCV	68.3	69.63	69.76	82–94 um3
MCH	22	21.31	20.656	27–31 PG/Ml
MCHC	32.2	30.6	29.61	32–36%
PLTS	251	230.6	289	150–400 ×103
Neutrophils	49.1	70.2	44.4	45–65%
Lymph	33.7	20.1	36.6	25–45%
Monocytes	6.6	9.06	16.5	0–6%
Eosinophils	0.15	0.18	0.231	0–2%
Basophils	1.11	0.601	2.13	0–1%
RDW	15.8	15.41	15.33
CRP	22.2	12.6	4.5	up to 6 mg/l
Electrolytes
Na	137	138	139	132–148 mEq/l
K	4.72	3.5	3.6	3.9–5.7 mEq/l
Cl		102	106	99–111 mmol/l
Chemistry
BUN	11	8		4.7–23.4 mg/dl
Creatinine	0.21	0.31		0.2–1 mg/dl
SGPT	9.2	29		0–45 uU/ml
SGOT	46.2	90		0–37 U/l
ALP		104		115–460 U/l

Those laboratory tests (haematological, CRP, electrolytes, and chemistries) were part of our patient non-imaging investigations.

ALP, Alkaline Phosphatase; BUN, Blood Urea Nitrogen; CBC, Complete blood count; CRP, C-Reactive Protein; HB%, Hemoglobin; HCT, Hematocrit; MCH, Mean Corpuscular Hemoglobin; MCHC, Mean corpuscular hemoglobin concentration; MCV, Mean corpuscular volume; PLTS, Platlets; RBC, red blood cell; RDW, Red cell distribution width; SGOT, Serum Glutamic Oxaloacetic Transaminase; SGPT, Serum Glutamic Pyruvic Transaminase; WBC, white blood cell.

On the next day of admission to our ward, the patient was ready for the surgery after the parent’s consent, which was done by the thoracic surgery team in our hospital. The patient underwent right thoracotomy and cyst excision, under general anaesthesia, incision was done at the right fifth postero-lateral intercostal space, with the finding of a huge cystic lesion (8×8×2.5) cm, attached with multiple adhesion to the posterior segment of the right upper lobe and the superior segment of the right lower lobe. The excision was done with a good safety margin in addition to fine adhesionolysis which was done using ligasure device (energy sealing device), no other pathology was seen (Fig. 2). Chest X-ray was done for follow-up on the operation day and postoperative day 4 (Fig. 1).

Figure 2.

Huge cystic lesion after complete surgical excision and the margins are free.

The Cyst was sent to the histopathology department for histopathological diagnosis, and the report came later with the diagnosis of PPB type 1 (PPB1). Sent in formalin and it was about (8×8×2.5 cm) cystic lesion. Sectioning shows a multilobular cysts, the largest one was 6.5 cm. All the surgical margins were free of malignancy.

Microscopic examination shows a multicystic lesion mostly composed of thin fibrous septae and lined by a benign cuboidal epithelium. The fibrous septae show mild cellularity with the presence of oval to spindle-shaped mesenchymal cells with the frequent subepithelial distribution. No solid areas were seen (Fig. 3). By immunohistochemstry, the epithelial elements are positive for CKAE1/3 and TTF1. Desmin and SMA highlight scattered, patchy mesenchymal cells in the subepithelium.

Figure 3.

Pleuropulmonary blastoma type 1. (A) Section shows thin fibrous cyst walls lined by a monolayer layer of flat to cuboidal epithelial cells (H&E, ×10); (B) Focal areas of increased subepithelial cellularity are noted (blue arrow); the epithelial lining is marked by the black arrow (H&E, ×20); (C) Foci of primitive mesenchymal cells characterized by round to oval nuclei and few amounts of cytoplasm are identified in a subepithelial location (H&E, ×40); (D) Desmin immune stain highlights occasional mesenchymal cells within the cyst walls (×20). H&E, hematoxylin and eosin staining.

Postoperatively, the patient was referred to paediatric oncology centre, where total body CT scan was performed and showed no residual disease, PET scan was performed and showed no pathological uptakes, the patient’s case was discussed in a multidisciplinary team meeting, and the decision was that there is no need for adjuvant chemotherapy or radiotherapy at this point providing that there is no evidence of active disease, but closely follow-up with monthly visit initially for the first 3 months, then alternating chest CT scan and Chest X-ray every 6 months for 5 years.

Three months follow-up showed no evidence of local recurrence or distal metastasis.

Discussion

PPB is a rare, aggressive malignant tumour, that occurs mostly in the paediatric population, accounting for 0.5–1 of all primary malignancies of the lung in children3,4,6. About 93% of PPB patients are under 6 years of age7, with no clear sex preference2.

The International PleuropulmonaryBlastoma Registry divides PPB into three types7, and a fourth type (Ir) was added in 20068, based on the cystic, solid and cystic and solid, with determination by the gross and microscopic examination, and all types have no specific symptoms of presentation3,9.

Type I tumours are purely cystic, lined by respiratory-type epithelium with consistent thin-walled structures, account for 15–20% of all PPB8, with a median age of diagnosis is 8 months10, also can occur in newborns11, peripherally located, and the absence of chest wall invasion is a specific characteristic and may be single or multicystic and the cyst wall is usually thin without grossly visible solid areas12, with 83% 5-year survival rate.

Type II tumours share combined features of both type I and III, with a median age of diagnosis is 35 months, as opposite to type I, type II can be attached to the chest wall or mediastinum, and can be presented as predominantly solid type II tumours or predominantly cystic type II tumours. Type III tumours are purely solid, well-circumscribed with hemithorax filling partly and aggressive attitude, and can be haemorrhagic or necrotic, which can make them more friable. Both type II and type III account for (80–85%) of PPB1, with a 2-year 42% survival rate11.

As type I PPB is the least common type11, which makes our case interesting, especially with the vague clinical presentation. All three types of tumours can present with nonspecific respiratory symptoms, such as difficulty of breathing, chest or abdominal pain, fever, cough, hemoptysis, anorexia, and also spontaneous pneumothorax especially in type I tumours, as shown in our child, when the first hospital admission was diagnosed as right pneumothorax and the patient was treated with chest tube insertion. As well as the patient may present with metastatic symptoms including neurological symptoms as the brain is the most common site of metastatic13.

There are no specific diagnostic protocol in the PPB, chest radiography is the first recommended step of evaluation, usually seen as hemi-opaque thorax on one side, with mediastinal deviation to the contralateral side14, type I appears as simple or multiple cystic lesions with fluid or air-filled, type II appears as a cyst with fluid and solid component that enhances with contrast, while type III appears as solid cyst surrounded with necrotic or haemorrhagic area. In the majority of the reported cases, the diagnosis is usually based on microscopic pathological findings in combination with radiological imaging and clinical findings, However, the pathological examination is the only tool that can confirm the diagnosis2.

Given the malignant nature of PPB, the recommended treatment is surgical excision, it is essential to reduce the recurrence rate and improve prognosis. Some studies support postoperative adjuvant chemotherapy and radiotherapy2,15, but other studies show no significant difference in mean survival between the surgical resection group versus surgery plus chemotherapy group15.

PPB type 1 usually shares a histological features with Congenital Pulmonary Airway Malformation type 4 so this morphological overlapping must be distinguishable. The differentiation cannot be done by clinical or imaging manifestation but only done based on pathological examination and discovery of DICER 1 gene mutation.

Some research studies suggested that PPB might result from a mutated DICER1 gene in at least one lung cell that is harmful to cell functions. Other research studies showed that PPB occurs due to unknown mechanisms of tumour induction.

Conclusion

We present a case of type I PPB, a rare but aggressive malignant tumour of the lung in the paediatric age group below 6 years. PPB can present with nonspecific clinical symptoms, so it could be misdiagnosed as pneumothorax, as in this case.

PPB should be considered as a differential diagnosis of cystic lesions in the paediatric age group. So imaging, clinical data, and histopathological diagnosis are mandatory, because early diagnosis and differentiation from another pulmonary cystic lesion, Congenital Pulmonary Airway Malformation, or other benign or malignant pulmonary masses are essential for management and treatment approaches determination and prognosis.

Ethical approval

The study is exempt from ethical approval in our institution.

Consent

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

Sources of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

Study concept or design: S.B. and Y.A.A. Data collection and data analysis: R.I.A.A., W.A. Writing the manuscript: R.I.A.A. and W.A.

Conflicts of interest disclosure

None declared.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Dr. Yousef AbuAsbeh.

Provenance and peer review

Not commissioned, externally peer-reviewed.