Pilot study comparing SPECT perfusion scintigraphy with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension.

BACKGROUND AND OBJECTIVE: The management of chronic thromboembolic pulmonary hypertension (CTEPH) is dependent on the extent of pulmonary artery obstruction, which is usually evaluated by planar perfusion scanning and CT pulmonary angiography (CTPA). We previously reported that SPECT perfusion scanning is more sensitive than planar scanning for detecting vascular obstruction in CTEPH. The purpose of this study is to compare SPECT with CTPA for detecting segmental pulmonary artery obstruction in CTEPH. METHODS: SPECT and CTPA were carried out before pulmonary endarterectomy in 12 CTEPH patients. Field experts documented the anatomical distribution of perfusion defects disclosed by SPECT, the anatomical distribution of pulmonary arterial filling defects disclosed by CTPA and the segmental anatomy of the vascular obstructions based on a review of clinical and pathology records, without knowledge of scan results. RESULTS: Clinical/pathological evaluation disclosed 140 obstructed (15.5 ± 2.5 per patient) and 40 unobstructed lung segments. SPECT scanning identified 87/140 (62%) of the obstructed and 29/40 (72%) of the unobstructed segments. By comparison, CTPA identified 67/140 (47.8%) of the obstructed and 32/40 (80%) of the unobstructed segments. Sensitivity for detecting obstructed segments was significantly higher for SPECT compared with CTPA (62 ± 4.1% vs 47.8 ± 2.9%, respectively; P = 0.03). CONCLUSIONS: SPECT is more sensitive than CTPA for identifying obstructed segments in this small sample of CTEPH patients. However, even SPECT under-represents the extent of vascular obstruction from this disease.

Pulmonary langerhans cell histiocytosis diagnosed in a cervical lymph node: a case report.

BACKGROUND: Pulmonary Langerhans cell histiocytosis (PLCH) is usually confined to the lungs and is therefore an unexpected finding in a cervical lymph node. CASE: A 52-year-old male with a 40-pack-year smoking history presented to our clinic with cough, fever and cervical lymphadenopathy. Chest computed tomography (CT) showed bilateral pulmonary nodules and enlarged mediastinal lymph nodes, worrisome for an infectious or malignant process. Bronchioloalveolar lavage was nondiagnostic. Fine needle aspiration cytology of the enlarged cervical lymph node revealed atypical histiocytoid cells, suspicious for malignancy. Immunohistochemistry revealed CD1a- and S-100-positive Langerhans cells. These findings, along with the patient's extensive smoking history and characteristic radiographic nodules, favored a diagnosis of PLCH with cervical lymph node involvement. The patient was advised to cease smoking, and no therapy was administered. Months later, follow-up chest CT showed spontaneous resolution of the lung nodules. CONCLUSION: The demonstration of Langerhans cells by immunohistochemical staining of CD1a and S-100 on a fine needle aspiration cell block is a useful diagnostic adjunct. In this case, definitive cytology for Langerhans cells in the appropriate clinical and radiologic setting allowed us to arrive at the correct diagnosis of PLCH in a minimally invasive manner.