Sean K. Lau

The clinical features of thyroglossal duct remnant cysts (TGDC) have been well described, however the histopathologic aspects of these lesions have not been addressed in a detailed manner. In particular, there has been no large community practice based series evaluating TGDC histologically compared with management outcomes. A retrospective review of all TGDC diagnosed between 2005 and 2015 was performed. Six hundred eighty-five patients were identified (344 males; 341 females). Age at presentation was bimodal (first and fifth decades) and ranged from 0.8 to 87 years (mean 31.3 years). Males predominate in children (150:111); females in adults (230:194). Patients presented most frequently with a mobile midline neck mass in an infrahyoid location. An associated skin fistula (n = 67) was twice as common in pediatric as adult patients. The average cyst size was 2.4 cm (range 0.4–9.9 cm) by imaging studies and 2.6 cm (range 0.2–8.5 cm) by pathologic examination; pediatric patients had smaller cysts (mean 2.1 cm) than adults (mean 2.8 cm). Histologically, 257 (38 %) TGDC were lined by respiratory epithelium alone, 68 (10 %) squamous epithelium alone, 347 (51 %) exhibited both respiratory and squamous epithelium, and 13 (1 %) had no identifiable epithelial lining. Four hundred eighty-four (71 %) TGDC had associated thyroid gland tissue present within the cyst wall (n = 282), skeletal muscle (n = 71), adipose tissue (n = 34), or a combination of these sites (n = 97). The hyoid bone was identified in 647 (grossly and/or histologically), and absent in 38. Surgical management consisted of Sistrunk procedure (n = 647), cystectomy (n = 31), or thyroidectomy/thyroid lobectomy (n = 7). Treatment related complications were observed in 6 patients, which included vocal cord damage, seroma, and hematoma. Recurrences developed in 20 (3 %) patients, 14 of whom were managed initially by cystectomy. Papillary thyroid carcinoma was identified in 22 (3.2 %) TGDC. In summary, TGDC show a bimodal peak in the 1st and 5th decades, commonly presenting as a midline cervical lesion below the hyoid bone, associated with a skin fistula in 10 %. Histologically TGDC are most commonly lined by a combination of respiratory and squamous epithelium. Thyroid gland tissue is identified in 71 % of cases (0.45 cm mean size), although not limited to the cyst wall, but present in the surrounding soft tissues. Rare TGDC may harbor malignancy (3.2 %). TGDC are most effectively managed by Sistrunk procedure rather than excision, which carries low rates of complications (1 %) and recurrence (3 %).

Spindle cell lipoma is a histologically distinct variant of lipoma characteristically arising in the subcutis of the posterior neck, upper back, or shoulder. Spindle cell lipomas infrequently occur within the oral cavity and, in particular, rarely involve the tongue. The clinical and pathologic features of eight cases of spindle cell lipoma affecting the tongue were analyzed. The study group included five men and three women ranging in age from 35 to 80 years (mean 57.4 years). Most lesions presented as either a painless or slowly growing lingual mass. The tumors were well circumscribed and characterized microscopically by a mixture of mature adipocytes, cytologically bland spindle cells, and interspersed bundles of thick collagen fibers in variable proportions. Myxoid stroma was a prominent feature in three lesions. The spindle cells were positive with CD34, while negative with S-100 protein, desmin, and smooth muscle actin. Treatment consisted of local excision in all cases. There have been no recurrences to date, with clinical follow up information available for all patients (range 11–118 months; mean 50.8 months). Lingual examples of spindle cell lipoma should be distinguished from other fat containing spindle cell neoplasms that can arise at this anatomic site.

Oncocytic lipoadenoma is an exceedingly uncommon neoplasm of the salivary gland composed of oncocytic epithelium and adipose tissue. Retrospective. Seven cases of oncocytic lipoadenoma were analyzed in order to further characterize the clinical and pathologic features of this rare tumor. The patients included six males and one female who ranged from 40 to 83 years of age (mean 62 years) at presentation. All tumors arose in the parotid gland. Grossly, the tumors were solitary, well circumscribed and had light brown to yellow cut surfaces. Histologically, the tumors were composed of an admixed population of oncocytes and adipocytes in varying proportions, with the lipomatous component ranging from 5 to 70 %. Other common features included the presence of serous acini, ductal elements, sebaceous glands, and a patchy chronic inflammation. Clinical follow up information, available in all cases, with a duration of 3–148 months (mean 57 months), showed no evidence of tumor recurrence. Due to its rarity, oncocytic lipoadenoma can pose problems in diagnosis, although the distinctive morphologic features of this neoplasm allow for separation from more commonly recognized oncocytic neoplasms of the salivary glands.

Immunohistochemical expression of napsin A in primary pulmonary mucinous tumors is not well established. Napsin A immunoreactivity was evaluated in 43 mucin-producing adenocarcinomas of the lung consisting of 18 tumors formerly classified as mucinous bronchioloalveolar carcinoma, 15 colloid adenocarcinomas, 5 solid predominant adenocarcinomas with mucin production, and 5 adenocarcinomas with signet ring cell features, as well as in 25 extrapulmonary mucinous adenocarcinomas of different anatomic sites. Immunohistochemical expression of thyroid transcription factor 1 (TTF-1) was also compared. Thirty-three percent of mucinous lung tumors exhibited positive immunoreactivity for napsin A, whereas 42% expressed TTF-1. All 25 extrapulmonary mucinous adenocarcinomas lacked expression of napsin A and TTF-1. Mucin-producing neoplasms of the lung infrequently express napsin A, suggesting that immunohistochemical assessment of napsin A may have limited diagnostic usefulness for distinguishing primary and metastatic mucinous adenocarcinomas involving the lung.