Benign Lung Neoplasms 5
Figure 5.1a — Papillomatosis, Bronchial Brushing [Pap Stain; Low Power]. Three-dimensional bifurcating papillary stalks are immediately noticeable in this large microfragment of tissue. Single cells exfoliated from these branching fronds are also numerous. These neoplasms may be solitary or multiple and are more likely in children and adolescents, but may occur in adults also. As squamous papillomas arise in both major and minor bronchi, their exophytic polypoid-like protrusions into the bronchial lumen allow for this florid architectural branching.
Figure 5.1b — Papillomatosis, Bronchial Brushing [Pap Stain; High Power]. High power magnification shows cells that have exfoliated as single forms and in loose clusters. Cells have the appearance of squamous metaplasia with a modest amount of opaque cytoplasm and rounded nuclei. Admixed with these metaplastic squamous cells are histiocytes and an occasional ciliated bronchial cell. The inset shows evenly dispersed nucleoplasm and smooth nuclear outlines. Though not present in this field, koilocytic change typical of low-grade squamous intraepithelial lesions would not be unusual because of the well-established association of pulmonary squamous papilloma with low-risk human papillomavirus, particularly human papillomavirus-6 and human papillomavirus-11.
Figure 5.1c — Papillomatosis, Resection [H&E Stain; Low Power]. Tracheobronchial papillomatosis is an uncommon complication of laryngeal disease. The papillomas harbor human papillomavirus types 6 or 11, and are morphologically similar to the laryngeal lesions. This endobronchial biopsy shows characteristic fragments of acanthotic squamous epithelium covering a hyalinized fibrovascular core. The oriented fragments show orderly maturation. Bronchoscopically, the mucosa may appear velvety or shaggy; postobstructive inflammatory changes and even bronchiectasis may supervene.
83Figure 5.1d — Papillomatosis, Resection [H&E Stain; High Power]. The maturing cells at the surface of this papilloma show human papillomavirus cytopathic effect, with koilocytosis and nuclear hyperchromasia with “raisinoid” features. High grade dysplasia in a papilloma, associated with human papillomavirus-16 and -18, is associated with partial or failed maturation, and is graded according to the World Health Organization classification of preinvasive lesions.
Figure 5.2a — Pulmonary Hamartoma, Fine Needle Aspiration [Pap Stain; Medium Power]. Pulmonary hamartoma is the most common benign neoplasm of the lung. Most are solitary, incidental findings, but multiple lesions have been described, particularly in patients with Carney syndrome. Hamartomas may be endobronchial or intra-parenchymal and radiographically are smoothly contoured, leading to their description as a “coin” lesion. When present radiographically, speckled (so-called “popcorn”) calcifications are diagnostically useful. Hyaline-type cartilage and adipose tissue are the two most common components of hamartomas, and as seen here cartilage may be abundant, or minimal in amount, as seen in the next image.
Figure 5.2b — Pulmonary Hamartoma, Fine Needle Aspiration [Diff-Quik Stain; High Power]. Most hamartomas are 3 cm or less in diameter, though larger lesions have been reported. Cellularity is variable and can be dispersed in loose or tight clusters and as single cells. The cellular component is composed of cytologically bland isomorphic cells, but in some cases high cellularity is possible, simulating the possibility of low-grade malignancy such as carcinoid tumor. These cells are derived from bronchiolar or alveolar cells and typically lack cilia. A concentrated search for a mesenchymal component usually allows for a specific diagnosis. In contrast to the prior image, only a small wispy fragment of chondromyxoid stroma is present in this case.
Figure 5.2c — Pulmonary Hamartoma, Fine Needle Aspiration [Diff-Quik Stain; High Power]. This image shares all three components of a pulmonary hamartoma: mature adipose tissue (most noticeable on the right), a cluster of monotonous epithelial cells (center), and myxoid/chondromyxoid stroma (upper left). The stroma is more opaque and chondroid in centrally located hamartomas, and more myxoid or myxohyaline in peripheral lesions.
Figure 5.3(a, b) — Hamartoma, Fine Needle Aspiration [Diff-Quik Stain; Medium Power]. The smears show abundant magenta-colored, fibrillary matrix material surrounding bland-appearing epithelioid cells with a thin rim of blue cytoplasm. If this were taken from the salivary gland, it would be strongly suggestive of a pleomorphic adenoma. There is also significant overlap with chondrosarcoma (discussed in Chapter 7). Examination of other fields or fine needle aspiration passes may reveal secondary components more suggestive of hamartoma.
Figure 5.3c — Hamartoma, Fine Needle Aspiration [Diff-Quik Stain; Low Power]. This field contains a large amount of acellular magenta-colored, fibrillary matrix that has the quality of matrix material seen in a pleomorphic adenoma. Given that this sampling was taken from a hamartoma, the matrix material is likely chondroid in origin. Chondroid matrix material can have many different appearances. This highlights the challenge of definitively identifying the origin of background material. For instance, the misidentification of mucinous material as chondromyxoid could lead one far down the incorrect diagnostic path.
Figure 5.3d — Hamartoma, Fine Needle Aspiration [Pap Stain; High Power]. This fragment of cartilage appears denser and less myxoid than the cartilaginous matrix seen in the previous images. It is also more definitively identifiable as cartilaginous material, given the presence of Swiss cheese-like holes within the matrix. If seen on a separate pass from the same lesion as in the previous images, this would cause one to consider a hamartoma rather than a pleomorphic adenoma. Unfortunately, this could also represent contamination from the normal cartilage if the needle has passed through a large airway, in which case the differential diagnosis remains between hamartoma and pleomorphic adenoma.