To the Editor:
We report the recent case of a 74-year-old female who had no relevant history of smoking
or occupational history and presented to the emergency room with a two-week history
of
dyspnea on exertion. There was no evidence of a recent respiratory infection, peripheral
edema, or orthopnea. The patient reported a history of arterial hypertension and
osteoporosis and was being treated with ramipril, fluvastatin, and ibandronate.
Physical examination revealed that the patient was apyretic and breathed normally,
with
an SpO2 of 98%, a blood pressure of 116/68 mmHg, and an HR of 91 bpm. In
addition, heart auscultation was regular, without heart murmurs and with absent breath
sounds at the right lung base, accompanied by dullness to percussion and absent vocal
fremitus in this topography.
A chest X-ray showed a dense opacity in the lower half of the right lung field,
consistent with massive, apparently free pleural effusion.
An initial diagnostic thoracentesis revealed a serosanguineous exudative effusion
(pH,
7.33; proteins, 4.5 g/dL; lactate dehydrogenase, 728 IU/mL; glucose, 38 mg/dL; albumin,
3.0 g/dL), with a predominance of lymphocytes (60%) and an adenosine deaminase level
of
10.6 IU. The first cytopathological analysis was negative, as was the microbiological
study.
The patient had a neuron-specific enolase level of 16 U/mL and a cancer antigen 125
level of 124 U/mL. Blood gas analysis indicated mild hypoxemia on room air. Flexible
bronchoscopy showed only thickening of the emergence of the right upper lobe bronchus,
the biopsy of which showed hyperplasia of basal cells.
The second cytopathological analysis of the fluid obtained via a second thoracentesis
led to the suspicion of papillary adenocarcinoma of unknown origin. A chest CT scan
(Figure 1) revealed right pleural effusion
without nodular pleural thickening or mediastinal/hilar adenopathy, and the assessment
of the lung parenchyma was inconclusive because of effusion-related atelectasis.
Figure 1
Chest CT scans. In A and B, initial CT scan showing right pleural effusion
with ipsilateral parenchymal atelectasis. In C and D, post-drainage CT scan
showing residual sites of pleural effusion with a nodular formation in the
medial segment of the middle lobe, with contrast enhancement.
By this time, the working diagnoses were papillary adenocarcinoma of the thyroid with
pleural metastasis, papillary adenocarcinoma of the lung with pleural and thyroid
metastasis, or synchronous papillary adenocarcinoma of the lung with pleural metastasis
and papillary adenocarcinoma of the thyroid.
On the basis of those diagnoses, the pleural fluid was examined for expression of
tumor
markers, including squamous cell carcinoma, Cyfra 21-1, CA 19-9, and thyroglobulin
(TG),
and the patient was referred for medical thoracoscopy and ultrasonography of the thyroid
gland.
The thyroid ultrasonography showed heterogeneous nodular hyperplasia, and aspiration
biopsy of the largest nodule revealed "primitive/secondary" papillary carcinoma, which
was subsequently confirmed (in a total thyroidectomy specimen) to be primitive papillary
carcinoma of the thyroid with immunohistochemical expression of thyroglobulin, TTF-1,
CK19, and galectin-3 (Figure 2).
Figure 2
Photomicrographs showing papillary adenocarcinoma of the lung in A
((H&E; magnification, ×20) and papillary adenocarcinoma of the thyroid in B
(H&E; magnification, ×100).
The pleural fluid was negative for thyroglobulin but positive for Cyfra 21-1 and CA19-9.
The medical thoracoscopy revealed nonspecific nodular lesions at the level of the
parietal pleura, and the pleural biopsies revealed metastatic papillary adenocarcinoma
of the lung, on the basis of positive expression of TTF-1, vimentin, and CK7 and
negativity for TG.
A second CT scan, performed after drainage of the fluid, made it possible to unveil
a
subpleural nodular formation in the medial segment of the middle lobe, with contrast
enhancement, suspected to be the primitive lung injury.
Therefore, we established the diagnosis of synchronous papillary adenocarcinoma of
the
thyroid and stage IV papillary adenocarcinoma of the lung with pleural metastasis.
The
patient underwent pleurodesis and began chemotherapy with cisplatin and gemcitabine,
with partial response after three cycles.
Although distant metastases of papillary adenocarcinoma of the thyroid are rare, cases
presenting as malignant plural effusion have been reported,(
1
-
5
)
and, in some cases, the final diagnosis was only confirmed by analysis of a total
thyroidectomy specimen.(
1
) In
contrast, lung adenocarcinoma is the type of cancer that most commonly metastasizes
to
the pleura, resulting in poor prognosis,(
6
) and its papillary variant is unusual. There are reported cases
associated with thyroid metastases.(
5
,
7
,
8
)
We emphasize that, in cases like the present one, with diagnosis of synchronous cancers
showing the same pattern of differentiation, etiologic determination of malignant
pleural involvement is of utmost importance because, even in disseminated disease,
the
difference in mean survival between papillary adenocarcinoma of the thyroid (a 5-year
survival rate of 56%) and papillary adenocarcinoma of the lung with pleural
dissemination (an average of 3-5 months) is remarkable.
In circumstances in which diagnostic discrimination is poor, such as that of the present
case, analysis of immunohistochemical expression is a key differentiating element.
In
particular, since TTF-1 is expressed in the lung and in the thyroid, the finding of
TG
in the pleural fluid, and especially in the histological specimen, can facilitate
the
differential diagnosis.(
9
)