Mucinous adenocarcinoma of the lung presenting as pathological humeral fracture: a case report and novel surgical treatment

Abstract

We present a 73-year-old woman who presented with a pathological fracture of her right humerus. Further imaging and biopsy indicated a mucinous adenocarcinoma of the lung as the primary neoplasm. This represents the first published case of a mucinous adenocarcinoma of the lung presenting as a metastatic lesion of the humerus. Operative management of pathological fractures of the humerus has typically included either intramedullary nailing or the use of single-plating or double-plating techniques. The authors describe a novel technique using both intramedullary fixation augmented with a locking plate, steel cables and bone cement, with good outcome.

Background

As the field of oncology continues to advance, life expectancy for patients with bony metastases is increasing, making operative management of such lesions evermore relevant. The humerus is the second most common site for long bone metastases, and the main aims of surgical treatment of pathological fractures are to allow good function of the limb and to reduce pain.¹ Common primary tumours which metastasise to the humerus include breast carcinoma, prostate cancer, renal cell carcinoma and lung adenocarcinoma.² Fractures of the humeral head and neck are often treated with endoprostheses, whereas diaphyseal lesions are mostly treated with intramedullary fixation or plate fixation, with or without bone cement augmentation.¹ There is currently no definitive consensus as to the optimal management of pathological diaphyseal fractures with an absence of multicentre randomised trials in the literature.³ This case represents the first published case of a mucinous adenocarcinoma of the lung presenting as a pathological humeral diaphyseal fracture. We also describe a novel surgical technique of using intramedullary medullary nailing, locking plate fixation and bone cement augmentation.

Case presentation

We present a 73-year-old independent woman who is a carer for her son. She has a background of vitamin D deficiency and is a smoker with a 50-pack-year history. She was leaning on her bed when her right arm gave way; she heard a ‘pop’ and experienced right arm pain. She reported previous pain in her right elbow and had associated weight loss over the past month. There was a clear deformity to her right elbow. She was admitted to the hospital by ambulance and was diagnosed with a distal humeral fracture after radiographs were taken (figure 1A, B). She was initially managed with analgesia and a cast was applied.

Figure 1.

Preoperative elbow radiograph: (A) anteroposterior and (B) lateral.

She underwent a CT (figure 2A, B) and subsequently an MRI scan of the right humerus (figure 3A, B), which showed a pathological distal humerus fracture as well as skip lesions proximally in the humerus. A CT of the chest, abdomen and pelvis identified a right upper lobe and hilar mass, suggesting a primary lung cancer which has metastasised to the right humerus. A T9 vertebral lesion was also noted, which was being managed conservatively.

Figure 2.

Preoperative CT scan: (A) coronal and (B) sagittal images.

Figure 3.

Preoperative MRI scan humerus coronal images: (A) T1 weighted and (B) fat suppressed.

Endobronchial ultrasound and biopsy confirmed the diagnosis as a mucinous adenocarcinoma of the lung.

The case was discussed in a multidisciplinary meeting consisting of several upper limb orthopaedic specialists, and the benefits and risks of operative and conservative management were discussed with the patient. The agreed plan was to fix the distal humerus fracture with a locking plate, with cables and bone cement augmentation, and to stabilise the proximal lesion with an intramedullary nail. It was felt this approach would give her the best functional outcome and pain relief and avoid fracture through the proximal lesion in the future. Due to the complexity of the case dual consultant operating was recommended and undertaken.

Meticulous preoperative planning with MERGE PACS software (IBM, Watson Health, USA) allowed visualisation of where the plate and cables should be applied and how the intramedullary nail could be locked distally, taking their position into account.

We used the validated patient-reported functional outcome score called the Quick Disability of the Arm, Shoulder and Hand (QuickDASH) questionnaire. The QuickDASH score was 63 immediately prior to surgery. This represents severe functional and pain problems from the patient’s perspective.

Treatment

A posterior approach to the distal humerus was used; the ulna and radial nerves were identified and protected throughout the procedure. The tumour was curetted at the fracture site, and a six-hole Depuy-Synthes LC-DCP Extra-Articular Distal Humeral Posterolateral (J) plate (DePuy Synthes, Raynham, Massachusetts, USA) was applied after anatomical reduction (figure 4A, B). Biomet Opti-PAC antibiotic impregnated cement was used to fill in the distal bone defect (figure 4A, B). Proximal bicortical screws and four distal locking screws were used. An anterolateral approach to the shoulder was used and the Multiloc Depuy-Synthes Humeral nail (DePuy Synthes) was inserted, making sure that there was adequate overlap of the plate and nail (twice the diameter of the bone) (figure 5A, B). The nail was locked with three proximal and two distal screws through the jig distally (figure 6A, B); two stainless steel Synthes cables were passed around the humeral shaft at the level of the two proximal plate holes through stainless steel eyelets located in the locking screw holes to provide additional stability (figure 5A, B). The fascia and skin were closed in a standard technique.

Figure 4.

Intraoperative C-arm images of (A) anteroposterior and (B) lateral views of the distal humerus with arrows showing the reduction of fracture and cement augmentation.

Figure 5.

Intraoperative C-arm images of (A) lateral and (B) anteroposterior views of the midshaft of the humerus with arrows showing nail plate overlap with cables.

Figure 6.

Intraoperative C-arm images of (A) anteroposterior and (B) lateral views of the proximal humerus with arrows showing the locking screws through the nail.

Outcome and follow-up

Postoperatively, the patient gradually increased her range of motion, with weight-bearing to begin at 6 weeks.

At 2 weeks postprocedure, her QuickDASH score was 38.6, which represents a significant improvement in her pain and function, and she was completely pain-free in her right arm. There were no postoperative complications. Postoperative radiographs at 2 weeks are shown in figure 7A, B, illustrating the full-length images of the surgical fixation.

Figure 7.

Postoperative radiographs: (A) anteroposterior and (B) lateral views showing the full fixation construct.

Discussion

The humerus represents one of the most common sites for pathological tumour-associated fractures in the body. For metastatic tumours, the most common primaries include renal cell carcinoma, prostate cancer, lung cancer and breast cancer.⁴ Simple bone cysts and enchondromas represent other common benign causes of a pathological humerus fracture. Diagnostic work-up for any patient with a suspected pathological fracture of a long bone includes CT and biopsy to diagnose a primary source, bone scan and/or positron emission tomography–CT to identify dissemination status (according to local protocol), and CT of the involved bone and fracture site if required.⁵ In the case described, CT of the chest, abdomen and pelvis identified a lung mass which was subsequently biopsied and revealed a mucinous adenocarcinoma of the lung. To the authors’ knowledge, this case is the first published incidence of a metastatic mucinous adenocarcinoma of the lung presenting as a pathological humerus fracture; small and large cell lung cancers are most commonly associated with skeletal metastases, which usually occur via haematogenous dissemination.⁶ The lumbar spine is the most common site for bony metastasis of bronchogenic carcinoma, with the proximal humerus being rarely involved.⁶

The main goals of treatment are immediate reduction of pain by stabilising the fracture, return to mobility with full weight-bearing as soon as possible, reducing morbidity, facilitation of nursing care and restoration of function.⁷ The surgical management of pathological humeral fractures largely involves either intramedullary nailing or single-plate or double-plate fixation, with or without augmentation with bone cement. Research in the field has focused on comparing outcomes between intramedullary nailing and plate fixation with a meta-analysis finding the two treatment methods to be largely comparable with regard to rates of non-union, infection and radial nerve injury for humeral shaft fractures. There is some evidence to suggest that closed reduction and intramedullary nailing represent a reliable treatment method for diaphyseal fractures, whereas open reduction and plate fixation are a superior method for treating metaphyseal fractures.³

The authors describe the use of intramedullary nailing combined with plate fixation, steel cables and bone cement augmentation to provide biomechanical stability to a complex fracture with a proximal skip lesion in the same bone. This technique for stabilisation of a pathological humeral fracture has not been described in the literature previously. Augmentation with bone cement is a well-established method in cases of pathological fractures to provide additional stability¹ by filling bone defects.

Learning points.

• Our case highlights that, although a rare entity, mucinous adenocarcinoma of the lung can metastasise to long bones, including the humerus.

• Furthermore, our case acts as an example to others faced with complex pathological fracture patterns, along with skip lesions in a long bone, that intramedullary nailing can be combined with plate osteosynthesis, cables and bone cement augmentation to provide stability.

• Preoperative planning using modelling software is invaluable in such cases to allow innovative techniques to manage complex fracture patterns.

Ethics statements

Patient consent for publication

Obtained.