Solid Epithelial Nests Research Articles

Acute Appendicitis and Periappendicitis Revealing Squamous and Transitional Cystic and Solid Nests in Adult Patients: Metaplasia or Vestigeal Remnants?

Squamous metaplasia of the appendix serosa is rare. We aimed to report the clinical and morphological features of 3 such cases. The patients presented with abdominal pain (n = 1 man, 2 women; age range, 29–35 years). The clinical diagnosis was appendicitis/periappendicitis (in the context of hydro/pyosalpinx). The surgical resected appendix showed several cystic and solid epithelial nests (1 mm and less) in the serosa/subserosa. Epithelial cells expressed p63, cytokeratin 5/6, as well as cytokeratins 7, 20, and CD10. Cystic and solid squamous and transitional epithelial nests of the appendix subserosa/serosa in adult patients may be revealed by acute appendicitis/ periappendicitis. The presence of such lesions, metaplastic or vestigial in nature, should be acknowledged since they can be misdiagnosed with metastatic epithelial tumor nests or they may undergo malignant change.

Basaloid squamous cell carcinoma of the maxillary sinus: Report of two cases in association with cathepsin K expression

Basaloid squamous cell carcinoma (BSCC) is a rare variant of squamous cell carcinoma. The occurrence of BSCC in the nasal cavity is extremely rare. In the present study, two cases of BSCC occurring in the maxillary sinus are reported and the clinicopathological features and immunohistochemical characteristics of this rare tumor are discussed. Two patients, aged 85 (case 1) and 60 years (case 2), presented with nasal tumors and persistent nasal obstruction. In each case, the biopsy or resected specimen of the maxillary sinus tumor revealed an infiltrative proliferation of solid epithelial nests composed of basaloid cells exhibiting hyperchromatic nuclei without conspicuous nucleoli and scant cytoplasm. Mitotic figures were frequently observed and spherical hyalinized materials were present within the tumor nests. Immunohistochemically, the tumor cells exhibited diffuse positive immunoreactivity for p63 and perinuclear dot-like positivity for vimentin, leading to a final diagnosis of BSCC of the maxillary sinus. Furthermore, it was demonstrated for the first time in the two cases that cathepsin K, a cysteine protease with marked collagenolytic and elastolytic activities, was expressed in a diffuse manner. One patient (case 2) succumbed to multiple metastases, while the other (case 1) remains alive with the disease. In conclusion, it was demonstrated that cathepsin K was immunopositive in two cases of BSCC of the maxillary sinus and that it may be involved in tumor invasion by this highly aggressive carcinoma.

Basal cell adenoma of the palate – a case report

AbstractWe report a case of basal cell adenoma of the palate in an 11‐year‐old girl. An 11 mm (diameter) round mobile, nontender mass was removed from the soft palate. Histologically, a well‐encapsulated tumour composed of solid epithelial nests with nuclear palisading, and ducts, in loose connective tissue stroma was found. Postoperatively, the patient was followed for 2 years. There were no signs of recurrence.

下顎臼歯部に生じたｄｅｎｔｉｎｏｇｅｎｉｃ ｇｈｏｓｔ ｃｅｌｌ ｔｕｍｏｒの１例

Dentinogenic ghost cell tumor (DGCT) is a rare lesion regarded to be a variant of calcifying odontogenic cyst (COC). However, some investigators recommend that DGCT should be distinguished from COC, because DGCT shows more aggressive behavior than ordinary COC. DGCT trends to occur in elderly persons and is composed mainly of ameloblastoma-like solid epithelial nests containing numerous ghost cells and dentinoid tissue. In this report, we present a case of DGCT in the mandibular molar region.A 73-year-old woman was referred to us because of a tender tumor mass in the mandibular molar region. An elastic soft oval tumor, measuring 20×12 mm, was found in the gingiva near the lower left third molar. The covering mucosa of the lesion showed slight redness. On the panoramic X ray film, a clearly demarcated semicircular radiolucent lesion with many radiopaque spots was observed in the left side of the mandible. The lesion was excised under local anesthesia. The postoperative course was uneventful, with no recurrence.

Serous borderline tumors of the ovary: a long-term follow-up study of 137 cases, including 18 with a micropapillary pattern and 20 with microinvasion.

The natural history of serous borderline tumors (SBTs) of the ovary varies considerably. A group of investigators have proposed that a small subset of SBTs with a micropapillary architecture and an allegedly higher incidence of invasive peritoneal implants should be designated "micropapillary serous carcinomas." Based on the overall favorable prognosis of the nonmicropapillary SBTs, these investigators have recommended abandoning the borderline category of serous tumors, restricting them to benign (benign and typical SBTs) and malignant types; other investigators, however, are in favor of retaining the original grouping, designating borderline tumors with a micropapillary pattern as such instead of designating them carcinomas. We have reviewed the clinicopathologic records of 137 patients with ovarian SBTs and obtained follow-up information on 106 of them ranging from 1 to 18 years (mean 7 years). Of the 21 patients with stage I tumors who had conservative surgical treatment, only two (9.5%) were subsequently found to have tumor in the contralateral ovary. Both were successfully managed by reoperation alone. Forty-five stage I patients had procedures that included bilateral oophorectomy, and two of them (4.4%) had a pelvic recurrence, which was fatal in one patient (whose tumor had been understaged) and occurred on multiple occasions in the other patient, finally transforming into invasive carcinoma; that patient survived. Of the 45 stage II-IV patients, only the six (13%) with invasive implants had an unfavorable outcome: three died of tumor (from 7 to 9.3 years), and the other three were alive with progressive disease from 5 to 10 years. Solid epithelial nests or small papillae surrounded by clefts and micropapillary architecture were found more often in invasive than in noninvasive implants. However, the only feature specifically associated with a poor outcome was obvious destructive invasion of the underlying tissue. Among the 137 SBTs, we identified 18 cases of serous borderline tumors with a micropapillary pattern (SBT-MP) (so-called "micropapillary carcinoma") and 20 cases of SBT with microinvasion (SBT-Minv) (three of which were also micropapillary). We compared the two groups of tumors with the remaining 102 cases of typical SBTs (which lacked micropapillary pattern and microinvasion). Of the 17 patients with SBT-MP and follow-up data, only the one patient with invasive implants had an unfavorable outcome; similarly, of the two patients with SBT-Minv and an unfavorable outcome, one had invasive implants and the other had been incompletely staged. SBTs have a very favorable prognosis, but complete surgical staging and prolonged follow-up are advised because pelvic recurrence and occasionally transformation to invasive carcinoma may occur. Designation of SBTs as "atypical proliferative tumors" is not recommended because it discourages complete surgical staging and follow-up. Advanced stage tumors with noninvasive implants are common, characteristically behave in a benign fashion, and can be safely treated conservatively. The rare SBTs associated with invasive implants are almost always fatal. SBT-MP and SBT-Minv are much closer in their biologic behavior to SBTs than to serous carcinomas. The micropapillary pattern alone does not imply an unfavorable prognosis; only micropapillary tumors associated with invasive implants behave aggressively.

Keratocystoma of the Parotid Gland: A Report of Two Cases of an Unusual Pathologic Entity

Benign salivary gland tumors composed of purely squamous cells are quite unusual and are not included in the World Health Organization classification. We have seen two benign parotid gland tumors characterized by multicystic spaces with stratified squamous linings and focal solid epithelial nests. Seifert et al. recently described such a case as a choristoma; we, however, herein propose a new designation, keratocystoma, for this unique tumor group, because of its distinctive histological features. These tumors occurred in men aged 18 and 38 years with enlarging parotid gland tumors. Both had largely similar gross and histological features, with some variations. The epithelium lining of the cysts showed apparent keratinization through a parakeratotic or orthokeratotic pathway without forming a granular cell layer. Stratification of the epithelium was always regularly oriented from the outer basal to the inner keratotic cell layer. Focally, the outer layer had bud-like protrusions. In some areas, solid squamous cell islands surrounded by basement membrane were enclosed within the collagenous stroma. These cystic and solid structures were randomly distributed, showing no definite lobular architecture. All of the tumor cells had uniform, bland nuclei and abundant eosinophilic cytoplasm. Scattered mitotic figures were observed, limited to the outer epithelial layer, and showed no abnormal patterns. Transformation from the parotid ductal epithelium to the tumor cells is evident. Foci of foreign-body reactions against keratin materials were present. Immunoreactivities for cytokeratins reconfirmed the nature of squamous differentiation of the tumor cells. Ki-67-positive cells were confined along the outer basal layer of the tumor epithelium. Tests for α-smooth muscle actin and S-100 protein were completely negative. Both patients had no evidence of recurrence 3 and 2 years after subtotal parotidectomy, respectively, without any additional therapy. We believe that this lesion represents a benign cystic neoplasm rather than a malignant tumor or pseudoneoplastic metaplastic condition. It is important to recognize that this peculiar benign tumor does originate from the salivary gland.

Refined diagnostic criteria for implants associated with ovarian atypical proliferative serous tumors (borderline) and micropapillary serous carcinomas.

Characterization of invasive peritoneal implants from patients with noninvasive serous ovarian tumors has important prognostic and treatment implications, but the criteria for distinguishing invasive and noninvasive implants vary among investigators and can be difficult to apply. The authors studied 148 implants from 60 patients, 33 with primary atypical proliferative serous tumor, and 27 with primary noninvasive micropapillary serous carcinoma, with a mean follow-up of 62 months (median follow-up, 52 months). Previously reported and newly proposed histologic features for implant classification were evaluated and correlated with clinical outcome. Three criteria were applied for the diagnosis of "invasive" implants: invasion of underlying normal tissue, micropapillary architecture, and solid epithelial nests surrounded by clefts. Implants displaying any one of these three features were classified as "invasive," whereas those lacking all three features were classified as "noninvasive." Sixty-six implants were invasive and 82 were noninvasive. Of the 31 patients with invasive implants, six were dead of disease (DOD), 13 were alive with progressive disease (AWPD), and 12 were alive with no evidence of disease (NED). Of the 29 patients with noninvasive implants, two were DOD, one was dead of uncertain causes, one was AWPD, and 25 were alive with NED. Eighty-nine percent of invasive implants had a micropapillary architecture and 83% had solid epithelial nests surrounded by clefts. A minority of invasive implants (14% of those with underlying normal tissue) demonstrated invasion of normal underlying tissue. Nuclear atypia, mitoses, calcification, necrosis, and identification of individual cells "infiltrating" the stroma did not correlate with implant type. The proposed criteria permitted recognition of implants that correlated strongly with adverse outcome. Sixty-one percent of patients with implants displaying any one of the three features used to diagnose invasive implants were AWPD or DOD compared with 10% of patients whose implants lacked these features (p = 0.00001). Because implants associated with an adverse outcome can be identified before they invade underlying normal tissue, the term invasive implant to describe them is inaccurate and misleading. These implants resemble patterns of growth in micropapillary serous carcinoma of the ovary and the recurrent tumor that is obvious carcinoma. Accordingly, we propose that these extraovarian lesions be designated "well-differentiated serous carcinoma."

Immunolocalization of Extracellular Matrix Components in Mixed Tumors of the Skin

Mixed tumors of the skin are characterized by a proliferation of epithelial cells embedded in a mesenchymal matrix with a wide spectrum of histologic appearances. The characterization of the extracellular matrix components of mixed tumors of the skin has so far received little attention. We performed an immunohistochemical study of type IV collagen, laminin, fibronectin, and tenascin distribution in a series of 10 mixed tumors of the skin. Laminin localized at the basement membrane around solid epithelial nests and tubulo-alveolar structures, whereas type IV collagen, fibronectin, and tenascin were also expressed in the myxoid stroma. Tenascin and fibronectin localized in the chondroid matrix. The extracellular matrix components were prominently expressed in mixed tumors of the skin, suggesting that they could play an important role in the formation and organization of myxoid and chondroid matrices and in the epithelial-mesenchymal interactions of these tumors.

The histologic typing of tonsillar carcinoma.

In a retrospective review of 170 cases of malignancies of the tonsil the authors report on 81 malignant epithelial tumors. In 56 cases (69.1%), the tumor (squamous cell carcinoma) was composed of solid epithelial nests with different degrees of keratinization. In 24 cases (29.6%) the tumor (undifferentiated carcinoma of nasopharyngeal type) had histologic characteristics similar to the undifferentiated carcinomas observed in the nasopharynx. Only one case was unclassifiable. Squamous cell carcinomas occurred more frequently in males (6:1), in older age, with more frequent extratonsillar and nodal extension and a poorer prognosis. Undifferentiated carcinoma had a similar incidence in both sexes, occurred also at an early age, and more often seemed to be limited to the tonsil. The 10-year disease-free survival rate was 30% for undifferentiated carcinoma; all the patients affected by squamous cell carcinoma had a recurrence within 6 years of the diagnosis.