Radiology/Pathology Correlation

Unknown 18

A 49-year-old man was admitted to the hospital for recurrent left lower lobe pneumonia and left lower lobe collapse.

tumor

Figure 1. Thoracic CT

Contrast-enhanced, axial CT (soft tissue windows) shows an enhancing lesion nearly occluding the left mainstem bronchus, with consequent near-complete collapse of the left lung.

Find the lesion.

 

mucousplugmucousplug

Figure 2. Thoracic CT

Axial CT image at the level of the left lower lobe bronchus shows low attenuation mucoid occlusion of the left lower lobe bronchus due to the more proximal obstructing lesion.

Find the occluded left lower lobe bronchus.

Virtual bronchoscopy and bronchoscopy with a flexible bronchoscope were performed.

What is the differential diagnosis?

Answer

 

 

Figure 3. Histology

A partial endoscopic resection yielded tissue showing a cellular tumor with scattered, thin-walled vascular channels. Note that the tumor forms nests separate from the stroma--an organoid pattern.

The surface epithelium was mostly intact.

Figure 4. Histology

Here the surface epithelium shows an abnormality. What is it?

Answer

What is the histologic differential diagnosis of this tumor?

Answer

Further examination of the tumor helped in the diagnosis.

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Glomus Tumors

Discussion: The glomus body, which is thought to regulate blood flow and temperature, is a neuromyovascular, arteriovenous structure present in the skin, and, less commonly, in other organs. One has been reported in the trachea [1]. Glomus tumors, composed of muscle cells resembling those in the glomus body, are unusual tumors that occur singly or multiply in the skin and subcutaneous tissue, especially the subungual region. Rarely, they occur in other parts of the body including the mediastinum, trachea, or lung. At least 7 glomus tumors, which presented with dyspnea, have been reported in the trachea [2], and 11 glomus tumors have been reported in the lung [3-5]. In the lung they are often confused with other bronchogenic or parenchymal lung tumors, especially carcinoid tumors. Patients with lung tumors ranged in age from 9 to 69 years, and 9 were male and 2 female. The tumors varied in size up to 9.5 cm, but most were less than 4 cm in diameter. One tumor occurred in a bronchus: the others were all parenchymal [5].

Histology and classification: The tumors are usually benign, but, rarely, may be infiltrative or malignant. Benign glomus tumors present as circumscribed nodules composed of polygonal cells with uniform, central nuclei, low nuclear/cytoplasmic (N/C) ratios, absent mitoses and variable numbers of thin-walled vessels. Mast cells are often interspersed in the tumor [3]. Atypical tumors have been classified as tumors of uncertain malignant potential or malignant glomangiosarcoma [4]. Mixed benign and malignant tumors have been described, as well [6]. In a study of 52 atypical or malignant cases from all parts of the body, criteria for malignancy consisted of the following: 1) deep location (such as lung) and size >2 cm, 2) atypical mitoses, or 3) marked nuclear atypia and 5 or more mitoses/50 high power fields. Tumors with one or more of the criteria for malignancy metastasized in 8 of 21 patients [4]. The tumor presented here was deep and had 14 mitoses/50 high power fields, indicating a malignant potential.

Radiologic findings: These tumors may present as solitary or multiple pulmonary nodules, or endobronchial lesions. The CT manifestations of glomus tumor are not specific, and almost any endobronchial lesion may present in a fashion similar to the glomus tumor in this case. One exception to this generalization is the endobronchial lipoma--the CT demonstration of a fat-containing lesion within the airway is highly suggestive of lipoma. The leading diagnoses for a proximal airway tumor are endobronchial squamous carcinoma or carcinoid tumor; the enhancement observed in this case would favor carcinoid over squamous carcinoma. Furthermore, an indolent lesion may be suspected in this case due to the lack of extraluminal tumor extension and the absence of regional lymphadenopathy. Nevertheless, biopsy and histopathological diagnosis are required for the vast majority of localized airway lesions.

Diagnosis: Routine H&E-staining of biopsies of tumors often yields an inconclusive diagnosis. Immunohistochemical tests, which show cytoplasmic reactivity for muscle specific actin (HHF35) and vimentin, help to differentiate these tumors from carcinoid tumors, hemangiopericytomas, and primitive neuroectodermal tumors [3,7]. Leiomyomas occur in the lung, but their histologic appearance with bundles of spindled, smooth muscle cells and lack of prominent vessels distinguishes them from glomus tumors. Ultrastructural features include cytoplasmic microfilaments, which form cytoplasmic dense bodies and plasmalemmal plaques; basement membrane around individual cells; and pinocytotic vesicles [1].

Behavior: Resection cures the benign glomus tumor. Recurrence of malignant tumors may be localized or widely metastatic. One 69-year-old man with primary glomangiosarcoma of the lung developed widespread metastatic disease and died 1 1/2 years later, despite chemotherapy [3]. Three other cases of malignant glomus tumors of the lung have been reported (38-year-old male (no follow-up), 9-year-old female, alive with metastasis at 60 mo [4], and 53-year-old male (disease free at 23 mo) [5]). Metastases to the lung from elsewhere have also been reported. A glomus tumor presented in the lung of a 19-year-old man as 2 nodules. It was followed one month later by infiltrating tumor in the buttock (the presumed primary) and then other cutaneous metastases [8].

Summary of histologic features of glomus tumors

Benign

Malignant

Final Diagnosis: Malignant glomus tumor (glomangiosarcoma), left main bronchus, partially resected.

Follow-up: A CT scan was performed 3 1/2 months after partial resection of the lesion.

References: To return to reference section after viewing abstract, click here before clicking on "abstract".

1. Kim Y, Kim J, Suh J, Ham E, Suh K. Glomus tumor of the trachea. Report of a case with ultrastructural observation. Cancer 1989; 64:881-886. Abstract

2. García-Prats M, Sotelo-Rodríguez M, Ballestín C, Martínez-González M, Roca R, Alfaro J, de Miguel E. Glomus tumour of the trachea: report of a case with microscopic, ultrastructural and immunohistochemical examination and review of the literature. Histopathology 1991; 19:459-464. Abstract

3. Gaertner E, Steinberg D, Huber M, Hayashi T, Tsuda N, Askin F, Bell S, et al. Pulmonary and mediastinal glomus tumors. Report of five cases including a pulmonary glomangiosarcoma: a clinicopathologic study with literature review. Am J Surg Pathol 2000; 24:1105-1114. Abstract

4. Folpe A, Fanburg-Smith J, Miettinen M, Weiss S. Atypical and malignant glomus tumors. Analysis of 52 cases, with a proposal for the reclassification of glomus tumors. Am J Surg Pathol 2001: 25:1-12. Abstract

5. Hishida T, Hasegawa T, Asamura H, Kusumoto M, Maeshima A, Matsuno Y, Suzuki K, et al. Malignant glomus tumor of the lung. Pathol Int 2003:53:632-636. Abstract

6. Gould E, Manivel J, Albores-Saavedra J, Monforte H. Locally infiltrative glomus tumors and glomangiosarcomas. A clinical, ultrastructural, and immunohistochemical study. Cancer 1990; 65:310-318. Abstract

7. Porter P, Bigler S, McNutt M, Gown A. The immunophenotype of hemangiopericytomas and glomus tumors, with special reference to muscle protein expression: an immunohistochemical study and review of the literature. Mod Pathol 1991; 4:46-52. Abstract

8. Mackay B, Legha S, Pickler G. Coin lesion of the lung in a 19-year-old male. Ultrastruct Pathol 1981; 2:289-294.

 

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Mucous plug distal to lesion

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Differential Diagnosis: The differential diagnosis of an endobronchial lesion within the left mainstem bronchus includes bronchogenic carcinoma (most often squamous carcinoma), carcinoid tumor, mucoepidermoid tumor, adenoid cystic carcinoma, an aspirated foreign body, and a host of benign mesenchymal tumors, such as lipomas or leiomyomas. Amyloidosis may produce a focal endobronchial lesion, although multifocal nodular or diffuse concentric airway narrowing is more common with this disorder. While a papilloma of the airway is generally included in the differential diagnosis of an endobronchial lesion, papillomas usually are not this large and do not show such vigorous enhancement.

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Squamous metaplasia

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Histologic Differential Diagnosis: The tumor was initially considered to be a carcinoid tumor, but special stains did not confirm this diagnosis. Other tumors considered were connective tissue tumors including tumors of fibroblasts or smooth muscle, glomus tumor, and hemangiopericytoma, as well as primitive neuroectodermal tumor. The possibility of metastatic tumor was also considered.

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