The incidence of primary tracheal tumors in the general population is not precisely known. Ranke and colleagues found 2 patients with tracheogenic carcinoma in 1,744 cancer deaths.7 Culp noted 4 patients with primary tracheal tumors in 89,600 autopsies.8 It is not a surprise that the diagnosis is seldom considered, even by pulmonologists.
The majority of primary tracheal tumors in adults are malignant. Thirty-six percent of a series of 198 patients with primary tracheal tumors seen at the Massachusetts General Hospital (MGH) over a 26-year period presented with primary squamous cell carcinoma (SCC) and 40% with adenoid cystic carcinoma (ACC).1 The remaining 24% of the total included 9 other malignant lesions, 17 of intermediate character, such as carcinoid and mucoepidermoid tumors, and 21 were clearly benign. None of the SCCs were secondary to laryngeal, bronchogenic, or esophageal carcinoma. By 2002, the number of ACCs and of SCCs seen had risen to 135 each, a total of 270 patients in these categories alone. The very wide variety of tumors other than SCC and ACC is noteworthy (Table 7-1). The pathology of primary tracheal tumors is reviewed in Chapter 3, "Pathology of Tracheal Tumors," and illustrated in a color fascicle. Bronchoscopic views of some tumors are also to be found in the color section. Tracheal tumors are even rarer in children. Two-thirds are benign, since of the most common adult tumors, ACC is only occasional in children and SCC is nearly unique. In a review of the literature and from their own experience, Desai and colleagues found only 38 children with tracheal tumors over a 30-year period.9 Over half were diagnosed initially as "asthma"; 39% were more than 50% obstructed when diagnosed. Hemangiomas and granular cell tumors were most common in the benign category, and mucoepidermoid tumors and histiocytomas in the malignant. Malignant tumors usually appeared in adolescence.
Primary SCC of the trachea may be exophytic or ulcerative, localized or longitudinally infiltrating, or less commonly, may show multiple areas of involvement scattered throughout the trachea (Figures 7-1, 7-2 and Figures 4 and 5, Color Plate 12). Invasive squamous cancer may also be found deep within what appears to be an area of papillomatous change, which on superficial biopsy reveals apparently in situ carcinoma. If such a lesion is grossly visible, it often does have deeper areas of invasive carcinoma.
As SCC grows, it extends longitudinally and circumferentially in the tracheal wall, and may penetrate extraluminally to involve adjacent structures. Tumors may occur at any level of the trachea or carina. Adjacent recurrent laryngeal nerves and the esophagus may be invaded directly. The most common sites of metastases are adjacent peritracheal lymph nodes. Hematogenous metastases to the lung, bone, liver, or adrenals are less common initially. Age and gender incidences of SCC of the trachea are similar to those of carcinoma of the lung (Table 7-2), with peak incidence between 50 and 70 years, predominating in males. The etiologies seem to be identical. Except in 4 cases, every patient we have seen with SCC of the trachea has been a cigarette smoker, usually for many years. One exception had received arsenicals for dermatolog-ic treatment in youth and suffered multiple squamous skin cancers on exposure to sunlight. Another had worked for many years with a multitude of organic chemicals and had previously suffered squamous carcinoma of his tongue base. In 2 other nonsmokers, no etiology was determined, although the extent of involvement of the overlying thyroid gland in 1 raised a question of whether that tumor might have been a primary squamous carcinoma of the thyroid invading the trachea. Forty percent of our patients with SCC
Table 7-1 Primary Tracheal Tumors other than Adenoid Cystic and Squamous Carcinomas
Small cell carcinoma
Basaloid squamous cell carcinoma
Malignant fibrous histiocytoma
Spindle cell sarcoma
Lymphoepithelial carcinoma Angiosarcoma
Solitary Pleomorphic adenoma Granular cell tumor (myoblastoma) Glomus tumor Fibroma
Fibrous histiocytoma (pseudotumor, plasma cell granuloma, xanthoma) Lipoma Leiomyoma Hamartoma Chondroma Chondroblastoma Schwannoma Neurofibroma
Paraganglioma Hemangioma Hemangioendothelioma Vascular malformation
Intermediate Malignancy Carcinoid Mucoepidermoid Plexiform neurofibroma Pseudosarcoma Plasmacytoma Acinic cell carcinoma of the trachea who underwent resection had either a previous history, a concurrent finding, or a later occurrence of SCC of the respiratory tract.1 Cancer arose in the tongue, tonsil, larynx, trachea (second primary lesion), and lung.
Basaloid squamous cell carcinoma, a rare and aggressive variant consisting of basaloid cells with either dysplastic epithelium or in situ squamous epithelium or invasive tumor, usually occurring in the upper aerodigestive tract, may be found in the trachea and may be deeply ulcerative, invasive, and metastatic.10 It may be confused with ACC histologically and with neuroendocrine carcinoma.
Adenoid cystic carcinoma may appear deceptively benign. Its former appellation, "cylindroma," masked its truly malignant character.1,11 Indeed, it used to be described clinically and pathologically under a general heading of "bronchial adenoma." This included a heterogeneous collection of "cylindroma," car-cinoid, and mucoepidermoid tumors plus a few true adenomas. Both terms are best abandoned. Adenoid cystic carcinoma of the trachea occurs over a wide age range, from the twenties through the seventies (see Table 7-2). Distribution between male and female is quite even but with female predominance (72 to 63 in 135 patients). No relationship has been discerned with cigarette smoking or other known carcinogenic factors. Thirty-three percent were smokers compared with at least 66% of patients with SCC. Although the
figure 7-2 Varied gross presentations of squamous cell carcinoma (SCC) of trachea. A, Tomographic delineation of a small exophytic lesion in a 60-year-old man. The "dome" of the subglottic larynx lies superiorly. The tumor (arrow) lies a few rings below the cricoid cartilage. B, Surgical specimen of A. An overlying lobe of thyroid was also removed in-continuity to provide a better lateral margin. Four years later, the patient underwent a right lower lobectomy for SCC of the lung. He died 20 years later without recurrence of either carcinoma.
figure 7-2 (continued) C, Smooth-appearing exophytic lower tracheal squamous carcinoma in a 56-year-old male. Right upper lobectomy was done 15 years later for squamous carcinoma. Neither tumor recurred. D, Tomogram showing a large squamous lesion of the lower trachea (between arrows) in a 55-year-old male. The lower open arrow marks the carina. E, Surgical specimen from D. The base of tumor was less extensive than gross tumor and provided a microscopically clear margin. F, Ulcerating squamous cell carcinoma in a 57-year-old man. Adjacent lymph nodes were involved. Three years later, he developed pulmonary metastases and a second primary squamous carcinoma of the tongue.
Incidence of Primary Tracheal Tumors by Age
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