An unusual case of pulmonary hamartoma with predominant bronchial mucous glands in the peripheral lung

Abstract

Pulmonary hamartoma (PH) is the most common benign lung tumor, comprising various amounts of mescenchymal components with entrapped epithelial components. We describe an unusual case of PH in the left lower lung lobe of a 60-year-old female. The tumor was 9 × 9 mm in size, light brown, weakly glistening, and microscopically found to be composed of well-developed epithelial and mesenchymal components without atypia. Both components were intermingled but without apparent transition. Epithelial components were occupied by predominant bronchial mucous glands. Serous glands, entrapped bronchioles, and clefts lined by respiratory epithelium were also apparent. Mesenchymal components including cartilage and fat were scattered, and swirling smooth muscle fascicles were interlaced with epithelial components. Collision tumor or other biphasic tumors were unlikely, and hyperplastic change in bronchial glands as in the rare conditions of intraoral minor salivary glands and epithelial entrapments by PH may explain these interesting histological findings. It is important to be aware of the possibility that a large number of bronchial mucous glands may be noted in the peripheral lung, and not to mistake this for other malignancies.

Mucinous Adenomyomatous Pulmonary Hamartoma: Clinicopathologic, Immunohistochemical, and Molecular Features of 6 Cases

“…A series of 6 patients with a solitary, peripheral PH consisting of a predominant smooth muscle proliferation strikingly associated with a proliferation of irregularly shaped and disperse mucinous columnar glands is reported in this article. Similar cases have been previously described under various names/definitions, such as “adenoleiomyomatous hamartoma,” “fibroleiomyomatous hamartoma,” “cystoadenomatous hamartoma,” and “pulmonary hamartoma with mucous glands.” 8,16-20 Another interesting case consisting of predominant mucous glands with a minority of smooth muscle was reported by Zhang et al 21 as “peripheral mucous gland adenoma with smooth muscle stroma.”…”

“…Similar cases have been previously described under various names/definitions, such as "adenoleiomyomatous hamartoma," "fibroleiomyomatous hamartoma," "cystoadenomatous hamartoma," and "pulmonary hamartoma with mucous glands." 8,[16][17][18][19][20] Another interesting case consisting of predominant mucous glands with a minority of smooth muscle was reported by Zhang et al 21 as "peripheral mucous gland adenoma with smooth muscle stroma. "…”

“…This unusual combination has been reported by Narita et al 17 in a cystic hamartoma, and the term “cystoadenomatous hamartoma” was proposed. Following these reports, a few other PH combining muscle and mucinous glands have been reported in literature under various designations, namely, “fibro/leiomyomatous hamartoma,” 18 “adenoleiomyomatous hamartoma,” 8,19 and “pulmonary hamartoma with mucous glands.” 20 Interestingly, Zhang et al 21 described a similar case as “peripheral mucous gland adenoma with smooth muscle stroma.”…”

“…22 Staining for basal cells was not included in all the aforementioned case reports, but none of the cases described pursued an aggressive cou rse. 2,8,[16][17][18][19][20][21] With this background, we collected a series of 6 leiomyomatous PH with a nonciliated mucinous proliferation lacking basal cells (mucinous adenomyomatous hamartoma), detailing on their immunohistochemical features and molecular alterations. The histogenesis, differential diagnosis, and prevalence of this unusual variant of PH were also discussed.…”

Renal Tumors with Oncocytic and Papillary Features: A Phenotypic and Genotypic Study

“…Collision tumors represent a biological enigma since two completely different histological counterparts of a single tumor are clearly separated [12]. The hypothesis of two separate neoplastic clones deriving from different cancer stem cells or the occurrence of an epithelial to mesenchymal transition isthe prevalent explanation for this rare phenomenon that may happen in many organs [11][12][13][14][15]. However, this hypothesis is hardly applicable to benign or low-grade malignant tumors such as the oncocytic and papillary renal neoplasms.…”