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An odd case of multiple “cannonball metastases”

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Q1: What abnormalities are seen on the radiograph?

The chest radiograph (see p 542) shows evidence of a raised left hemidiaphragm and a small left pleural effusion. Two pulmonary nodules, which have no visible calcification or cavitation but well defined margins, are noted overlying the left midzone. One lesion lies adjacent to and above the aortic knuckle, the other one adjacent to the left heart border.

A subsequent contrast enhanced spiral computed tomogram of her chest showed two small focal nodules in the right lobe, two moderate sized in the left upper lobe, and one large mass measuring approximately 6 × 9 × 11 cm replacing most of the left lower lobe, also a small left pleural effusion; there was no lymphadenopathy.

Q2: What is the differential diagnosis?

The differential diagnosis of multiple lung masses is quite complex, with metastatic disease being the most common cause. Other possibilities include an inflammatory process such as fungus, tuberculosis, nocardiosis, or septic emboli. In asymptomatic patients further considerations include the presence of arteriovenous malformations, rheumatoid nodules, or amyloidosis. Less common pulmonary lesions also include fibromas, chondromas, lipomas, hamartomas, and leiomyomas.

The radiological appearances as well as clinical features help to narrow the differential diagnosis down. On inspection of the radiograph one should note size, distribution, presence of cavitation, and that of calcification. Malignant tumours that commonly metastasise to the lung include breast, thyroid, gastrointestinal tract and renal cell carcinomas, also head and neck tumours and soft tissue sarcomas. Metastases are present in variable numbers and are usually well defined and peripheral in distribution. Cavitation is occasionally seen with squamous cell carcinomas and calcification is unusual except for chondrosarcoma and osteosarcoma metastasis. The main distinguishing features from benign lesions are the rate of growth and the presence of systemic symptoms. Hamartomas and carcinoid tumours have almost identical appearance on radiography, however most commonly these are solitary with hamartomas being peripheral and often calcified and carcinoid being perihilar. Other conditions that cause multiple lung lesions are lymphoid malignancies and Kaposi’s sarcoma. Finally infectious diseases including fungus granulomas, abscesses and hydatid disease and also connective tissue disorders should be mentioned. Fungus granulomas and hydatid disease may well be asymptomatic, while multiple abscesses will manifest with fever and symptoms pointing to their source. Rheumatoid nodules are usually small and rarely cavitate. Larger lesions are seen in Wegener’s granulomatosis, but those are characteristically cavitating and often associated with haemoptysis and other symptoms of systemic vasculitis.

Q3: What important piece of information from the patient’s past medical history is missing and would highlight a possible diagnosis?

The patient had had a total abdominal hysterectomy and bilateral salpingo-oophorectomy for uterine fibroids aged 49 years.

She also had had a right thoracotomy with a wedge resection for a 2 cm diameter encapsulated tumour at the age of 69 years. Histopathological examination revealed spindle shaped smooth muscle cells, fibroblastic elements, and glandular structures lined by low columnar epithelium. Review of slides from the uterine lesions removed at hysterectomy showed similar histology.

Q4: What is the most likely diagnosis?

Spindle cell proliferation consistent with pulmonary leiomyomata secondary to a benign metastasising uterine leiomyoma.

With only around 40 cases reported until 1996,1 metastasising uterine leiomyomata are fairly rare anatomical and clinical entities. This condition is rather peculiar because of two contradictory findings: the tumour’s benign histology and its metastasising capabilities. It is characterised by the early development of a uterine leiomyoma with the appearance of solitary or multiple pulmonary metastases in the premenopausal period.2 Most patients reported a hysterectomy three to 20 years before diagnosis.3 Although, like our patient, most of the cases were asymptomatic, presenting symptoms such as dyspnoea, dry cough, or chest pain have been reported.4 With its incredibly slow tumour growth rate and stabilisation in the menopausal period prognosis is good, although complications caused by metastatic pericardial involvement are possible.1

Q5: How would you treat this condition?

Uterine leiomyomas are known to be oestrogen sensitive. In fact, both oestrogen and progesterone receptors have been identified in lung lesions and have led to treatment based on hormonal manipulation with either surgical or medical oophorectomy.4

Secretion of the gonadotrophins, luteinising hormone and follicle stimulating hormone, is normally pulsatile, with major pulses released every 1–2 hours depending on the phase of the menstrual cycle. Long acting gonadothrophin releasing hormone analogue (GnRHa), produces down-regulation of the GnRH receptors and subsequent very low androgen or oestrogen levels. Evidence based data shows that GnRHa causes fibroids to shrink but cannot be used long term because of unacceptable symptoms and bone loss.5 Short term use over six months, however, has been shown to be the treatment of choice in pulmonary metastases to achieve remission and effective prevention of recurrences.6

Final diagnosis

Spindle cell proliferation consistent with pulmonary leiomyomata secondary to a benign metastasising uterine leiomyoma.

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