CT-pathologic correlation in nodular bronchioloalveolar carcinoma

CT Halo sign: A systematic review

PURPOSE

The CT Halo sign or Halo sign (HS) refers to ground-glass opacity surrounding a nodule or mass in the lung parenchyma. We conducted a systematic review to find the etiological associations of HS. We also evaluated the diagnostic performances of HS for invasive fungal infections (IFI) in immunosuppressed patients.

METHOD

The systematic review was conducted as per PRISMA guidelines. We searched the PubMed and EMBASE database till June 2018 without any restrictions. Only case reports, case series and original articles published in English language were included. A database created from the electronic searches was compiled and subsequent analysis was done. [PROSPERO registration: CRD42018094739] RESULTS: 168 studies were eligible, which included 51 case reports, 15 prospective studies, 102 retrospective studies. A total of 1977 patients (out of 6371) with HS were identified with age range between <1year-94years. The most common diagnosis in the immunosuppressed, mixed, immunocompetent and not specified groups were IFI (86.9 %, n = 1194), Cryptococcosis (51.6 %, n = 124), Cryptococcosis (40 %, n = 20) and lung neoplasms (81.8 %, n = 36) respectively. 14 studies (11 retrospective, 3 prospective) were included in quantitative analysis. The pooled sensitivity(sn), specificity(sp) and odd's ratio (OR) of HS for diagnosing IFI were 50.4 %, 91 % and 6.61 respectively. Also, HS could not reliably differentiate IPA from mucormycosis in the pooled analysis.

CONCLUSIONS

HS can be seen in a large number of diverse conditions both in immunosuppressed and immunocompetent population. In immunosuppressed patients HS is specific for IFI but cannot rule it out. Additionally, it cannot reliably distinguish between IPA and mucormycosis.

Persistent Pulmonary Nodular Ground-Glass Opacity at Thin-Section CT: Histopathologic Comparisons

PURPOSE

To retrospectively compare pure pulmonary ground-glass opacity (GGO) nodules observed on thin-section computed tomography (CT) images with histopathologic findings.

MATERIALS AND METHODS

The institutional review board approved this study and waived informed consent. Histopathologic specimens were obtained from 53 GGO nodules in 49 patients. CT scans were assessed in terms of nodule size, shape, contour, internal characteristics, and the presence of a pleural tag. The findings obtained were compared with histopathologic results. Differences in thin-section CT findings according to histopathologic diagnoses were analyzed by using the Kruskal-Wallis test or Fisher exact test.

RESULTS

Of 53 nodules in 49 patients (20 men, 29 women; mean age, 54 years; range, 29-78 years), 40 (75%) proved to be broncholoalveolar cell carcinoma (BAC) (n=36) or adenocarcinoma with predominant BAC component (n=4), three (6%) atypical adenomatous hyperplasia, and 10 (19%) nonspecific fibrosis or organizing pneumonia. No significant differences in morphologic findings on thin-section CT scans were found among the three diseases (all P>0.05). A polygonal shape (25%, 10 of 40 nodules) and a lobulated or spiculated margin (45%, 18 of 40) in BAC or adenocarcinoma with predominant BAC component were caused by interstitial fibrosis or infiltrative tumor growth. A polygonal shape and a lobulated or spiculated margin were observed in two (20%) and three (30%) of 10 nodules, respectively, in organizing pneumonia/fibrosis were caused by granulation tissue aligned in a linear manner in perilobular regions with or without interlobular septal thickening.

CONCLUSION

About 75% of persistent pulmonary GGO nodules are attributed to BAC or adenocarcinoma with predominant BAC component, and at thin-section CT, these nodules do not manifest morphologic features that distinguish them from other GGO nodules with different histopathologic diagnoses.

Current status of small peripheral adenocarcinomas of the lung and their importance to pathologists

There has been a large amount of work done recently on small peripheral stage I adenocarcinomas that come to resection. Radiological (including proportion of ground glass opacity) and pathological features of these lesions (predominant bronchioloalveolar component, central scar with or without invasion <0.5 cm) have been shown to be prognostically favorable with cure rate approaching 100% in some series. Most of these studies emanate from Japan. The relevance of these studies to other parts of the world, particularly North America, is discussed in light of the fact that some recent chemotherapeutic studies with gefitinib have shown increased response in individuals of Asian origin, suggesting that some genetic differences may be significant. The relevance of these findings to pathologists and the pathological study of small peripheral adenocarcinomas from elsewhere in the world are discussed.

CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules

OBJECTIVE

In the Early Lung Cancer Action Project (ELCAP), we found not only solid but also part-solid and nonsolid nodules in patients at both baseline and repeat CT screening for lung cancer. We report the frequency and significance of part-solid and nonsolid nodules in comparison with solid nodules.

MATERIALS AND METHODS

We reviewed all instances of a positive finding in patients at baseline (from one to six noncalcified nodules) and annual repeat screenings (from one to six newly detected noncalcified nodules with interim growth) to classify each of the nodules as solid, part-solid, or nonsolid. We defined a solid nodule as a nodule that completely obscures the entire lung parenchyma within it. Part-solid nodules are those having sections that are solid in this sense, and nonsolid nodules are those with no solid parts. Chi-square statistics were used to test for differences in the malignancy rates.

RESULTS

Among the 233 instances of positive results at baseline screening, 44 (19%) involved a part-solid or nonsolid largest nodule (16 part-solid and 28 nonsolid). Among these 44 cases of positive findings, malignancy was diagnosed in 15 (34%) as opposed to a 7% malignancy rate for solid nodules (p = 0.000001). The malignancy rate for part-solid nodules was 63% (10/16), and the rate for nonsolid nodules was 18% (5/28). Even after standardizing for nodule size, the malignancy rate was significantly higher for part-solid nodules than for either solid ones (p = 0.004) or nonsolid ones (p = 0.03). The malignancy type in the part-solid or nonsolid nodules was predominantly bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar features, contrasting with other subtypes of adenocarcinoma found in the solid nodules (p = 0.0001). At annual repeat screenings, only 30 instances of positive test results have been obtained; seven of these involved part-solid or nonsolid nodules.

CONCLUSION

In CT screening for lung cancer, the detected nodule commonly is either only part-solid or nonsolid, but such a nodule is more likely to be malignant than a solid one, even when nodule size is taken into account.

Bronchioloalveolar carcinoma and adenocarcinoma with bronchioloalveolar features presenting as ground-glass opacities on CT

OBJECTIVE

As bronchioloalveolar carcinoma (BAC) is noninvasive but, in its later stages, has a worse prognosis than adenocarcinoma with bronchioloalveolar features (ACB), early identification and differentiation is important for therapeutic and prognostic purposes. We wanted to identify features of BAC, which differentiated it from ACB when both presented as ground-glass opacities (GGOs) on CT.

MATERIALS AND METHODS

We reviewed all pathologic specimens of patients who were diagnosed with BAC and ACB in the lung from 1991 to 1999 in our institution and whose malignancy presented as a GGO on CT. This yielded 29 patients, 15 with BAC and 14 with ACB with GGOs on CT. Both univariate frequency table and multivariate logistic regression approaches were used to analyze the CT characteristics of these GGOs (location, GGO pattern, size, shape, margin, presence and type of air bronchogram and pseudocavitation).

RESULTS

BAC most frequently had a "GGO halo" around a solid opacity, often was a GGO "mixed with consolidation" with the smallest BACs being "pure GGO." Air bronchograms were frequently present in the largest GGOs. Pseudocavitations were rare. ACB, on the other hand, most frequently presented as a GGO "mixed with consolidation," less frequently with a "GGO halo" and rarely with "superimposed lymphangitis." The air bronchograms, frequently present, were usually tortuous and ectatic. Pseudocavitation was present in about one-third of the cases. The most useful CT features of GGO in separating those due to BAC from those due to ACB were pure (uniform) ground-glass attenuation and absence of lymphangitis.

CONCLUSION

The CT features of BAC and ACB presenting as GGO reflect the histologic descriptions of these carcinomas.

CARCINOMA BRONQUÍOLO-ALVEOLAR: ASPECTOS NA TOMOGRAFIA COMPUTADORIZADA DE ALTA RESOLUÇÃO

O carcinoma bronquíolo-alveolar é um tipo de carcinoma broncogênico de crescimento insidioso, que surge nas paredes das vias aéreas distais e se dissemina utilizando o septo alveolar como um estroma, preservando a arquitetura pulmonar. Neste trabalho foram analisadas as tomografias computadorizadas de alta resolução de 17 pacientes com carcinoma bronquíolo-alveolar. Ao contrário do relatado na literatura, foram observados predomínio no sexo masculino (71%) e maior freqüência da associação das formas de consolidação e multinodular (53%) em relação à forma nodular solitária (12%), multinodular (12%) e de consolidação (23%). Os aspectos mais encontrados foram: áreas de consolidação (76%), broncograma aéreo (71%), áreas de baixa atenuação provavelmente devidas à presença de muco (60%), espessamento de septos interlobulares, opacidades em vidro fosco e nódulos confluentes (54% cada), e pavimentação em mosaico (36%). Os nódulos cavitados, a atelectasia, o sinal do halo e o aspecto de "árvore em brotamento" foram observados em apenas um caso cada.

High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT

OBJECTIVE

The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns.

MATERIALS AND METHODS

We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed.

RESULTS

Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV).

CONCLUSION

Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.

Magnetic resonance imaging of bronchioloalveolar carcinoma

The purpose of this study is to describe the magnetic resonance (MR) features of bronchioloalveolar carcinoma. MR examinations of 18 patients with proven bronchioloalveolar carcinoma were reviewed. Detection at computed tomography (CT) and pathologic confirmation were the entry criteria. Nine patients had a solitary nodule, three patients a lobar consolidation, and six patients had diffuse disease. For each patient, both breath-hold T2-weighted fast spin-echo, and breath-hold T1-weighted gradient-echo images, before and after injection of gadolinium, were available. Nine patients with pulmonary consolidation or diffuse disease had also heavily T2-weighted MR imaging (Haste or TSE 240; Siemens, Erlangen, Germany). MR imaging showed pulmonary abnormalities in 17 of 18 patients. Unenhanced T1-weighted and T2-weighted images depicted tumor in 16 of 18 patients. Contrast-enhanced T1-weighted images showed tumor in 17 of 18 patients. In no case did MR imaging depict abnormalities corresponding to the ground-glass opacities seen on CT scans. In three patients with mucinous bronchioloalveolar carcinoma, heavily T2-weighted images showed lesions isointense with respect to static fluid of the human body. In conclusion, the ability of MR imaging in detecting small nodules and ground-glass opacities is limited. However, heavily T2-weighted sequences are able to show the presence of mucin. This is useful information because mucinous bronchioloalveolar carcinoma carries a poor prognosis.

Ground-glass attenuation in nodular bronchioloalveolar carcinoma: CT patterns and prognostic value

PURPOSE

The purpose of our study was to assess the CT patterns and prognostic value of ground-glass attenuation in nodular bronchioloalveolar carcinoma (BAC).

METHOD

We retrospectively reviewed CT examinations of 22 patients with 24 nodular BACs who underwent surgery. CT and pathologic findings were analyzed and correlated with postoperative course of disease.

RESULTS

We detected five patterns of ground-glass attenuation associated with nodular BAC: pure ground-glass nodule (n = 1), ground-glass nodule with superimposed lymphangitis (n = 1), nodule with mixed areas of ground-glass attenuation and consolidation (n = 2), ground-glass halo around nodule (halo sign) (n = 3), and nodule associated with a plurisegmental area of ground-glass attenuation (n = 1). Two patients with the halo sign and a third patient with a plurisegmental area of ground-glass attenuation rapidly developed diffuse pulmonary disease by bronchogenic spread and died a few months after surgery.

CONCLUSION

Our series demonstrates that focal BAC may progress to diffuse pulmonary involvement by bronchogenic spread. The presence of a large area of ground-glass attenuation associated with a nodular BAC might be the CT sign of an aggressive biologic behavior. In these cases there is a high likelihood for diffuse disease to develop from bronchogenic spread.

Pulmonary involvement of idiopathic hypereosinophilic syndrome: CT findings in five patients

PURPOSE

The aim of this study was to assess the CT findings of pulmonary involvement in patients with idiopathic hypereosinophilic syndrome (HES).

METHOD

The study included five patients with idiopathic HES who had pulmonary involvement proven by bronchoalveolar lavage (n = 3) or based on clinical and radiologic findings (n = 2). Four patients had high resolution CT and one had conventional CT. The CT scans were retrospectively reviewed by two chest radiologists for pattern and distribution of disease.

RESULTS

All five patients had several small nodules in both lungs at CT scan. Four patients had nodules with a halo of ground-glass attenuation. Three patients had focal areas of ground-glass attenuation in both lungs. These lesions were present in all lung zones and involved mainly the peripheral lung. There was neither lobar predilection nor peribronchovascular distribution. Other organs involved included bone marrow (n = 3), liver (n = 3), stomach (n = 1), and peritoneum (n = 1).

CONCLUSION

The CT findings of pulmonary involvement in patients with idiopathic HES included small nodules with or without a halo of ground-glass attenuation and focal areas of ground-glass attenuation mainly in the lung periphery.

Air-space pattern in lung metastasis from adenocarcinoma of the GI tract

PURPOSE

We retrospectively reviewed a series of proven lung metastasis to evaluate the frequency and CT features of metastases showing an air-space (lepidic) pattern of growth.

METHOD

CT examinations of 65 patients with proven lung metastasis from GI carcinomas were reviewed by three observers. Four CT features were used to classify lesions as air-space metastases: (a) air-space nodules; (b) parenchymal consolidation containing air bronchogram and/or showing angiogram sign; (c) focal or extensive ground-glass opacities; and (d) nodules(s) with a "halo" sign.

RESULTS

Six of 65 patients showed air-space metastases: three from pancreatic carcinoma, two from colonic carcinoma, and one from jejunal carcinoma. In one case, metastasis appeared as extensive parenchymal consolidation associated with ground-glass opacities; in one as an area of ground-glass opacity; in one as an extensive parenchymal consolidation with air bronchogram; in one as parenchymal consolidations with angiogram sign and multiple nodules, some of these with halo sign; in one as air-space nodules and patchy air-space consolidations; and in one as a solitary nodule with halo sign.

CONCLUSION

Our study shows that air-space lung metastasis from GI carcinomas is uncommon but not rare. On CT as well as microscopically, differential diagnosis between air-space metastasis and bronchioloalveolar carcinoma may be impossible.