Morules and morule-like features associated with carcinomas in various organs: report with immunohistochemical and molecular studies

Uniportal video-assisted thoracoscopic segmentectomy for fetal adenocarcinoma lung cancer with severe pulmonary emphysema: a case report

Background

Fetal adenocarcinoma is a very rare subtype of lung adenocarcinoma. Its incidence ranges from 0.1 to 0.87% among all primary lung neoplasms. Low-grade types tend to appear in the younger generation, and the age ranges from 20 to 50 years with a mean age of around 35 years. Surgical resection is currently the best way to treat fetal adenocarcinoma lung cancer without distant metastasis.

Case report

This is a 56-year-old female who underwent low-dose computer tomography (LDCT) screening during the health examination. She used to be a heavy smoker for more than 30 years, and the CT images revealed severe bronchiectasis and emphysema. There is a solitary nodule with a diameter of 18.9 x 17.8mm in the central area of the left upper lobe. We decided to conduct left upper lobe S1~S3 segmentectomy under uniportal VATS. The surgery was successful, and the patient was discharged within one week and recovered well. The final diagnosis was fetal adenocarcinoma, low-grade (pT1cN0Mx, stage IA3).

Conclusion

The first case reported as fetal adenocarcinoma lung cancer who underwent uniportal video-assisted thoracoscopic segmentectomy. We believe it is a safe and feasible procedure for low-grade types fetal adenocarcinoma patient with poor pulmonary function.

Colonic invasive adenocarcinoma with squamoid morules: A case report

Colorectal adenomas with squamoid morules are rare; however, colorectal adenocarcinomas are even rarer. Herein, we present a case of colorectal adenocarcinoma with squamoid morules arising from the transverse colon. A 60-year-old Japanese man underwent a colonoscopy, and a Type 0-Is polyp was detected in the transverse colon. The endoscopic findings suggested a high possibility of carcinoma invasion into the deep submucosa. However, endoscopic mucosal resection was performed due to the patient's preference. Histopathologically, the tumor cells mostly formed atypical glandular structures corresponding to adenocarcinomas. Solid nests were observed in parts of the tumor, composed of round, small to short spindles. Immunohistochemically, p63 was positive in some areas, CK20 was negative, and the Ki-67 positive cell rate was almost zero, suggesting a squamoid morule. Based on the above findings, colorectal adenocarcinoma with a squamoid morule was diagnosed; only the fifth case was reported worldwide. Squamoid morules should be carefully differentiated from squamous components of adenosquamous carcinomas.

Mesonephric-like adenocarcinoma of the ovary with squamoid morular metaplasia, aberrant β-catenin expression, and concurrent FGFR2 and CTNNB1 mutations: a case report

In general, endometrioid-defining features such as squamoid morular metaplasia are not thought to be associated with mesonephric adenocarcinoma (MA) and mesonephric-like adenocarcinoma (MLA). Here, we report a case of FGFR2-mutated ovarian MLA with squamoid morular metaplasia accompanied by aberrant nuclear and cytoplasmic β-catenin expression and CTNNB1 mutation. Histologically, the tumor showed classical MLA histology, including well-formed glands with intraluminal eosinophilic secretions and cells with papillary thyroid carcinoma-like nuclei. Squamoid morular metaplasia was intimately associated with the tumor. Glandular epithelial elements, including those immediately associated with the squamoid morules, were negative for ER, but positive for both GATA3 and PAX8; aberrant β-catenin expression was limited to the squamoid morules. This case illustrates the ability of mesonephric neoplasia to exhibit histological features previously thought to be restricted to an endometrioid phenotype.

Utility of a PAX2, PTEN, and β-catenin Panel in the Diagnosis of Atypical Hyperplasia/Endometrioid Intraepithelial Neoplasia in Endometrial Polyps

The diagnosis of atypical hyperplasia/endometrioid intraepithelial neoplasm (AH/EIN) within endometrial polyps (EMPs) often poses a diagnostic conundrum. Our previous studies demonstrated that a panel of immunohistochemical (IHC) markers consisting of PAX2, PTEN, and β-catenin can be effectively utilized for the identification of AH/EIN. A total of 105 AH/EIN within EMP were analyzed using the 3-marker panel. We also evaluated these cases for the presence of morules. Benign EMP (n=90) and AH/EIN unassociated with polyp (n=111) served as controls. Aberrant expression of PAX2, PTEN, or β-catenin was observed in AH/EIN in EMP in 64.8%, 39.0%, and 61.9% of cases, respectively. At least 1 IHC marker was abnormal in 92.4% of cases. Overall, 60% of AH/EIN in EMP demonstrated abnormal results for≥2 IHC markers. The prevalence of PAX2 aberrancy was significantly lower in AH/EIN in EMP than in nonpolyp AH/EIN (64.8% vs. 81.1%, P =0.007), but higher than in benign EMP (64.8% vs. 14.4%, P <0.00001). The prevalence of β-catenin aberrancy was significantly higher in AH/EIN in EMP than in nonpolyp AH/EIN (61.9% vs. 47.7%, P =0.037). All control benign EMP demonstrated normal expression of PTEN and β-catenin. Morules were present in 38.1% of AH/EIN in EMP versus 24.3% in nonpolyp AH/EIN, and absent in benign EMP. A strong positive association was found between β-catenin and morules (Φ=0.64). Overall, 90% cases of atypical polypoid adenomyoma (n=6) and mucinous papillary proliferation (n=4) showed IHC marker aberrancy. In conclusion, the 3-marker IHC panel (PAX2, PTEN, and β-catenin) is (1) a useful tool in the diagnosis of AH/EIN in EMP; (2) PAX2 loss should be interpreted with caution and in combination with morphology and other markers.

Morules but Not Squamous Differentiation are a Reliable Indicator of CTNNB1 (β-catenin) Mutations in Endometrial Carcinoma and Precancers

Although collectively regarded as "squamous differentiation (SD)" in endometrial endometrioid carcinoma (EEC) and atypical hyperplasia/endometrioid intraepithelial neoplasia (AH/EIN), morules (often referred to as "squamous morules") and true SD may represent two distinct phenomena. Here, we explored the distinction between morules versus SD and investigated the association of morules and SD with CTNNB1 mutations. A total of 270 cases of EEC and AH/EIN were studied, including EEC with (n=36) or without (n=36) morules and AH/EIN with (n=80) or without (n=118) morules. Cases were analyzed by immunohistochemistry and selected cases (n=20) by targeted next-generation sequencing panel. Near-perfect agreement was found between morules and glandular β-catenin nuclear staining in AH/EIN and EEC. A strong positive association was found between morules and glandular β-catenin nuclear staining (P<0.0001, Φ=0.59 in AH/EIN; P<0.0001, Φ=0.85 in EEC). There was no association between (1) morules and glandular PAX2 or PTEN aberrant expression or (2) SD and aberrant expression of β-catenin, PAX2 or PTEN (Φ=0.09, β-catenin; Φ=0.16, PAX2; Φ=0.13, PTEN). CTNNB1 mutations were identified in all 20 selected morule-containing cases (100%). Next-generation sequencing was performed on 2 (preprogestin and postprogestin treatment) biopsies from 1 patient, revealing identical mutational profile in morules and glands. In conclusion, (1) SD and morules are distinct biological phenomena; (2) the presence of morules, but not SD, is a reliable indicator of CTNNB1 mutations in EEC and AH/EIN. Our findings demonstrate that SD and morules are distinct biological phenomena. Since morules but not SD are associated with β-catenin mutations, the distinction is clinically relevant and should be included in diagnostic reports.

Clinicopathological, Radiological, and Molecular Features of Primary Lung Adenocarcinoma with Morule-Like Components

BACKGROUND

Morule-like component (MLC) was a rare structure in primary lung adenocarcinoma. We aimed to reveal the clinicopathological, radiological, immunohistochemical, and molecular features of lung adenocarcinoma with MLCs.

METHODS

Twenty lung adenocarcinomas with MLCs were collected, and computed tomographic and histological documents were reviewed. Immunohistochemistry, targeted next-generation sequencing, and Sanger sequencing for β-catenin gene were performed.

RESULTS

There were 9 lepidic adenocarcinomas, 8 acinar adenocarcinomas, 2 papillary adenocarcinomas, and 1 minimally invasive adenocarcinoma. Most patients (16/17) were shown a pure solid nodule, and 1 patient was shown a partly solid nodule on chest computed tomography (CT). Nine cases were accompanied with micropapillary components, and 3 were with cribriform components in which 2 suffered a worse prognosis. No significant association was found between the MCLs and the overall survival of lung adenocarcinoma (P = 0.109). The MLCs were often arranged in whorled or streaming patterns. The cells in MLCs showed syncytial and mild appearance. The MLCs were positive for E-cadherin, CK7, TTF-1, napsin-A, vimentin, and β-catenin (membrane), and negative for CK5/6, p40, p63, Synaptophysin, chromogranin A, and Cdx-2. EGFR mutation, ALK-EML4 fusion, HER2 amplification, and PIK3CA mutation were detected in 16 cases, 2 cases, 1 case, and 1 case, respectively. EGFR mutation was more frequent in adenocarcinomas with MLCs than those without MLCs (P = 0.040). β-catenin gene mutation was not detected in any patients.

CONCLUSIONS

MLC is often observed in the background of acinar, lepidic, and papillary adenocarcinomas. Lung adenocarcinomas with MLCs tend to appear as a solid mass on CT and harbor EGFR gene mutations. The micropapillary components and cribriform components may cause poor prognosis of lung adenocarcinomas with MLCs. Vimentin is always positive in MLCs, and it is a useful marker for the identification of MLCs.

Morule-like features in pulmonary adenocarcinoma associated with epidermal growth factor receptor mutations: two case reports with targeted next-generation sequencing analysis

Morules, or morule-like features, can be identified in benign and malignant lesions in various organs. Morular features are unusual in pulmonary adenocarcinoma cases with only 26 cases reported to date. Here, we describe two cases of pulmonary adenocarcinoma with morule-like features in Korean women. One patient had a non-mucinous-type adenocarcinoma in situ and the other had an acinarpredominant adenocarcinoma with a micropapillary component. Both patients showed multiple intra-alveolar, nodular, whorled proliferative foci composed of atypical spindle cells with eosinophilic cytoplasm. Targeted next-generation sequencing was performed on DNA extracted from formalin-fixed paraffin-embedded samples of the tumors. Results showed unusual epidermal growth factor receptor (EGFR) mutations, which are associated with drug resistance to EGFR tyrosine kinase inhibitors, revealing the importance of identifying morule-like features in pulmonary adenocarcinoma and the need for additional study, since there are few reported cases.

Incidence of composite intestinal adenoma-microcarcinoid in 158 surgically resected polyps and its association with squamous morule

Composite intestinal adenoma-microcarcinoid (CIAM) is a rare colorectal lesion consisting of adenoma and small well-differentiated neuroendocrine cell clusters at its base. Its incidence is unknown. Benign squamous morule may demonstrate a neuroendocrine phenotype by immunohistochemistry. We investigated the incidence and clinicopathologic features of CIAM in endoscopically unresectable, surgically removed colorectal adenomas and evaluated its association with squamous morule. Archived pathology materials from 158 surgically resected colorectal adenomas were reviewed. 139 (88%) polyps were entirely submitted for microscopic examination. All lymph nodes were negative for adenocarcinoma and neuroendocrine tumor. CIAM was identified in 6 (3.8%) cases. The microcarcinoid (MC) was distributed over a mean of 5.8 mm (range < 1 to 12 mm), and was multifocal in 5 cases. The MC component was positive for synaptophysin in 6, CK5/6 in 4, and β-catenin in 3 cases. Two of 6 (33.3%) CIAM showed concurrent squamous morule, compared to 4.0% (6 of 152) of adenomas without MC (p < 0.05). At the end of the mean follow-up of 53 months, 4 were free of disease and one patient with previous history of pulmonary large cell neuroendocrine carcinoma (NEC) had a recurrence of NEC. One patient died of an unrelated disease. The incidence of CIAM in surgically removed colorectal adenomas is 3.8%, with an indolent clinical course. Frequent co-expression of CK5/6 and β-catenin in MC combined with common co-existence of squamous morule in the same polyp suggests shared pathogenesis of MC in CIAM and squamous morule, likely representing altered Wnt/β-catenin signaling pathway.

Two Cases of Sinonasal Non-Intestinal-Type Adenocarcinoma with Squamoid Morules Expressing Nuclear β-Catenin and CDX2: A Curious Morphologic Finding Supported by Molecular Analysis

Sinonasal non-intestinal-type adenocarcinoma (non-ITAC) is a rare, morphologically diverse neoplasm of the head and neck. Squamoid morular metaplasia has recently been reported as an occasional finding in non-ITAC. Interestingly, these squamoid morules often show aberrant expression of CDX2 as well as nuclear expression of β-catenin, similar to other tumors that show this type of metaplasia, but the underlying mechanism responsible for this finding is not completely understood. We present two cases of low-grade non-ITAC with squamoid morules coexpressing CDX2 and nuclear β-catenin by immunohistochemistry, both of which were found to harbor a mutation in CTNNB1, the gene encoding β-catenin. This finding provides support that an alteration in the β-catenin pathway, including mutations in the β-catenin gene itself, is responsible for this recently described morphologic phenomenon in non-ITAC.

Comprehensive review of fetal adenocarcinoma of the lung

Fetal adenocarcinoma of the lung (FLAC) is a rare tumor. It accounts for ~0.1%-0.5% of all pulmonary neoplasms. Due to its rarity, much of the world literature regarding FLAC comes from case reports and case series. FLAC is an adenocarcinoma resembling developing fetal lung in its pseudoglandular stage (8-16 weeks of gestation). It is distinguishable from pulmonary blastoma (PB) because it lacks the mesenchymal component which is a hallmark finding in PB. Due to differences in histopathology and clinical course, FLAC has been further categorized into low-grade (L-FLAC) and high-grade (H-FLAC) forms. L-FLAC displays low nuclear atypia and prominent morule formation and has a pure pattern. H-FLAC typically presents with at least 50% fetal morphology, and is often associated with other conventional types of lung adenocarcinoma. FLAC expresses neuroendocrine markers and thyroid transcription factor 1 in most cases. L-FLAC has an aberrant nuclear/cytoplasmic expression of β-catenin and presents mutations in this gene. H-FLAC overexpresses p53. These tumors have a very low frequency of mutations in KRAS and EGFR; it is thought that they are different from a molecular point of view to conventional lung adenocarcinomas. Approximately 25%-40% of patients are asymptomatic at presentation; most of them are incidental findings on chest radiographs. H-FLAC is more common in elderly male patients, with a heavy smoking history. L-FLAC tends to occur in young females. Patients with L-FLAC are usually diagnosed with stage I-II disease, while patients with H-FLAC usually present with a more advanced-stage disease. Poor prognostic factors for FLAC are thoracic lymphadenopathy, metastases at diagnosis, and tumor recurrence; however, the 10-year survival for FLAC is estimated at 75%.

Squamoid morules in the pseudoinvasive foci of colonic polyp morphologically mimic invasive carcinoma

Colorectal adenomas can show focal squamous differentiation or squamoid morules. We describe histologic findings of squamoid morules in the pseudoinvasive foci of colorectal polyps mimicking invasive carcinoma. Five colonic polyps with squamoid morules in the pseudoinvasive foci were collected. Histologic review and immunostains for cytokeratin 5/6, p63, synaptophysin, and chromogranin were performed on cases with squamoid morules. Forty-seven consecutive colorectal polyps with pseudoinvasion, none of which showed squamoid morules by histology review, and their clinicopathologic features were compared with the cases containing squamoid morules. Cases with squamoid morules more frequently occurred in younger patients (P=.047) and were located in right colon (P=.027) than those without squamoid morules. Diagnosis of the polyps included tubular/tubulovillous adenoma with low-grade (with squamoid morules, n=3; versus without squamoid morules, n=29) or high-grade dysplasia (n=2 versus n=15) and sessile serrated adenoma (none versus n=3). Squamoid morules formed nodules protruding into the lumen of glandular structures or partially replaced adenomatous glands without forming a discrete nodule. They also presented as solid nests showing a well-formed morular structure around the bottom of adenomatous glands or myxoinflammatory stroma. Importantly, squamoid morules often formed a pseudocribriform or solid nest sitting in the stroma of pseudoinvasive foci. All cases (n=4) showed cytokeratin 5/6 positivity and p63 negativity in squamoid morules. Three and 1 of 4 cases showed focal positivity for synaptophysin and chromogranin, respectively, in squamoid morules. Squamoid morules in colonic adenomatous polyps can mimic invasive carcinoma when present in the pseudoinvasive foci. Pathologists should be aware of their presence.

Shadow cell differentiation from squamoid morule in endometrial adenoacanthoma

Shadow cell differentiation (SCD), commonly found in cutaneous pilomatricoma (PMX), has been said to be extremely rare in extracutaneous tumors and its morphogenesis has not been clarified yet. In the present study, 25 cases of endometrial adenoacanthoma were examined with special reference to SCD and with immunohistochemistry for beta-catenin and CD10. Shadow cell nests (SCNs) were observed in 2 out of 5 cases of adenocarcinoma with squamoid morules and all of 4 cases of adenocarcinoma with squamous differentiation and morules, but not in any cases of adenocarcinoma with squamous differentiation. SCNs were just adjacent to morules with or without a mutual transition. Immunohistochemical examination revealed nuclear accumulation of beta-catenin and expression of CD10 in the squamoid morules around SCNs. These results indicate that SCNs are derived from squamoid morules in endometrial adenoacanthoma, and established a link between matrical basaloid cells in PMX and squamoid morules in endometrial adenoacanthoma, as common original tissues, showing nuclear accumulation of beta-catenin and expression of CD10, of SCNs. It seems that SCD is not so uncommon as previously estimated in endometrial adenoacanthoma.

The pericyte antigen RGS5 in perivascular soft tissue tumors

Perivascular soft tissue tumors are relatively uncommon neoplasms of unclear lineage of differentiation, although most are presumed to originate from or differentiate to pericytes or a modified perivascular cell. Among these, glomus tumor, myopericytoma, and angioleiomyoma share a spectrum of histologic findings and a perivascular growth pattern. In contrast, solitary fibrous tumor was once hypothesized to have pericytic differentiation--although little bona fide evidence of pericytic differentiation exists. Likewise the perivascular epithelioid cell tumor (PEComa) family shares a perivascular growth pattern, but with distinctive dual myoid-melanocytic differentiation. RGS5, regulator of G-protein signaling 5, is a novel pericyte antigen with increasing use in animal models. Here, we describe the immunohistochemical expression patterns of RGS5 across perivascular soft tissue tumors, including glomus tumor (n = 6), malignant glomus tumor (n = 4), myopericytoma (n = 3), angioleiomyoma (n = 9), myofibroma (n = 4), solitary fibrous tumor (n = 10), and PEComa (n = 19). Immunohistochemical staining and semi-quantification was performed, and compared to αSMA (smooth muscle actin) expression. Results showed that glomus tumor (including malignant glomus tumor), myopericytoma, and angioleiomyoma shared a similar diffuse immunoreactivity for RGS5 and αSMA across all tumors examined. In contrast, myofibroma, solitary fibrous tumor and PEComa showed predominantly focal to absent RGS5 immunoreactivity. These findings further support a common pericytic lineage of differentiation in glomus tumors, myopericytoma and angioleiomyoma. The pericyte marker RGS5 may be of future clinical utility for the evaluation of pericytic differentiation in soft tissue tumors.

Transition between morule-like and solid components may occur in solid-predominant adenocarcinoma of the lung: report of 2 cases with EGFR and KRAS mutations

A limited number of pulmonary adenocarcinoma cases with morule-like components have been described to date, and the most frequent histological subtype is papillary-predominant adenocarcinoma. Occasionally, this type of adenocarcinoma is associated with solid-predominant adenocarcinoma. EGFR mutations are predominant in adenocarcinoma with morule-like components, followed by ALK rearrangements. Herein, we present 2 cases of solid-predominant adenocarcinoma with morule-like components harboring either an EGFR or KRAS mutation. This KRAS-mutant case is the first to be associated with morule-like components, to the best of our knowledge. Both cases showed transition between micropapillary and morule-like components. Transition between morule-like and solid components was also observed in both cases. Although a few cases of solid-predominant adenocarcinoma have been shown to harbor morule-like components, this type of transition has not been previously well described. We surmised that the solid components of some EGFR-mutant adenocarcinomas might be derived from morule-like components.

Squamous morula formation in colorectal adenoma: Immunohistochemical and molecular analyses

Little is known about the squamous morular component (SMC) in colorectal neoplasms because of its rarity. The aim of the present study is to elucidate the morphological, immunohistochemical and genetic characteristics of SMCs in colorectal adenomas. Five colorectal adenomas having SMCs were resected from five patients endoscopically. On immunohistochemical examination (four cases), all SMCs were positive for cytokeratin 5/6 in their cytoplasm and positive for β-catenin in their cytoplasm and nuclei. A nuclear positivity of p63 was detected in one SMC. All SMCs were negative for p53, chromogranin A, synaptophysin and NCAM. There was no Ki-67 expression in any of the SMCs. We detected none of mutations of β-catenin, KRAS and BRAF by microdissection and polymerase chain reaction-direct sequence in any of the four examined SMCs. SMCs are a rare but problematic finding in colorectal adenomas. Using immunohistochemistry for β-catenin, cytokeratin 5/6, Ki-67, p53, chromogranin A, synaptophysin and NCAM can facilitate the diagnosis of these peculiar cell nests.

Non-sarcomatous spindle cell morphology in conventional lung adenocarcinoma: a clinicopathological study

Non-sarcomatous spindle cell foci (N-SSCF) without aggressive invasiveness, also called morule-like lesions, occur occasionally in conventional lung adenocarcinoma, but their characteristics remain poorly understood. We identified N-SSCF in 7 (4.0 %) of 173 lung adenocarcinomas and examined their clinicopathological features. The patients were six men and one woman with a mean age of 57.0 years (range, 43-76 years). All tumors were papillary-predominant adenocarcinomas, ranging in size from 1 to 4.5 cm (mean, 2.7 cm). N-SSCF occupied 10-30 % of the tumors, and in all cases, there were focal or multifocal transitions between the two morphotypes. Most N-SSCF were plug-like nodules filling the spaces of cancerous alveoli/tubules or patchy insular nests. N-SSCF frequently contained mucin + lumina and were positive for cytokeratin 7, thyroid transcription factor 1, and Napsin A, but negative for cytokeratin 5/6 and vimentin, similar to the adenocarcinoma cells of the same tumor. Five cases (71 %) were at stage I or II, suggesting that N-SSCF can occur in an early phase of lung cancer. In an age-, sex-, and stage-matched control study, N-SSCF were not associated with prognosis (P = 0.471). We consider tumors with N-SSCF a distinct structural variant of adenocarcinoma without prognostic significance. They should be distinguished from true sarcomatous spindle cells and micropapillary components, which are associated with aggressive behavior.

Primary lung adenocarcinoma with morule-like components: a unique histologic hallmark of aggressive behavior and EGFR mutation

BACKGROUND

Lung adenocarcinoma with morule-like components is an unusual variant of lung adenocarcinoma, comprising uniform, tightly packed spindle-shaped cells, which fill the lumen of the glandular structures of the carcinoma. The aim of the study was to outline the clinicopathologic features of this variant.

PATIENTS AND METHODS

We examined a series of 904 surgically resected adenocarcinomas. We defined morule-like components as small buds of spindle-cell proliferation in the tumor lumen of the glandular structures of the carcinoma and calculated their proportion of total tumor mass. Targeted genotyping was performed for KRAS, EGFR, HER2, and BRAF. ALK rearrangements were analyzed immunohistochemically. Immunopositive cases were confirmed using RT-PCR and/or FISH.

RESULTS

We detected 17 cases of adenocarcinoma with morule-like components. This variant, representing only 1.9% was associated with unfavorable outcomes and a mutation in the EGFR. Histologic examination revealed adenocarcinoma with morule-like components accounting for 5-50% of tumors. Among the morule-like components, 10 (58.8%) of the 17 samples showed intracytoplasmic lumina formation containing eosinophilic mucinous material. The presence of micropapillary components in adenocarcinoma with morule-like components suggests that morule-like components could be merely excessive growth of the micropapillary pattern. However, our results indicated no statistical differences in the MIB-1 indices of the morule-like components and the adjacent tumor components or the micropapillary components. The univariate and multivariate analyses revealed a correlation between the presence of a morule-like components and an unfavorable outcome.

CONCLUSIONS

Our study clearly indicated that adenocarcinoma with morule-like components is distinct unfavorable prognostic and predictor for EGFR mutation.

Morule-like features and tumor-associated lymphoid proliferation in gallbladder carcinoma

A unique case of gallbladder carcinoma with morule-like features and tumor-associated lymphoid proliferation in a 53-year-old man is presented. The surgically resected gallbladder demonstrated a polypoid tumor with a thin stalk, measuring 1.3 x 0.5 cm. Histologically, a well-differentiated tubular adenocarcinoma was accompanied by multiple spindle cell nodules. The stroma of the tumor showed dense lymphocytic infiltrate. Immunohistochemically, the spindled cell nodules were diffusely positive for cytokeratin AE1/AE3 but negative for S-100, NSE, and chromogranin A. The immunohistochemical results considered to be spindle cell nodules were morule-like features. Intranuclear expression of beta-catenin was observed in morule-like features and carcinoma cells. Ki-67 labeling index was 16.7% of carcinoma cells, but Ki-67 immunoreactivity was negative in spindle cell nodules; therefore, morule-like features were considered to represent metaplastic foci of carcinoma cells and not nodular growth of carcinoma cells. Although the exact pathogenesis of marked lymphoid proliferation in the stroma remained unknown, tumor-produced substances may derive from lymphoid proliferation.

[Alveolar adenoma -- a rare lung tumour]

INTRODUCTION

Alveolar adenoma belongs to the group of benign epithelial tumours. Histogenesis of alveolar adenoma is a combination of proliferation of alveolar pneumocytes and fibrous tissue originating from septal mesenchyma.

CASE OUTLINE

A sixty-nine-year old female patient was hospitalizied for clinical examination and surgery of well defined and homogenous tumourous lesion in the right middle lobe causing pleural pain. Bronchoscopic examination with biopsy did not resolve aetiology of the disease. Tumourectomy was performed. Tumourous nodule had a multicystic appearance and histologically, histochemically and immunohistochemically, an alveolar adenoma was estimated. Five years after surgery, the patient feels well, without respiratory symptoms and signs of recurrence or malignant alteration, respectively.

CONCLUSION

Alveolar adenoma is a rare benign lung tumour, most frequently presented as a solitary pulmonary nodule. After complete surgery, the tumour neither relapses nor malignantly alters. Surgical excision is curative. It is necessary to take into consideration alveolar adenoma, too, when a solitary pulmonary nodule is diagnosed.

An immunohistochemical study of morules in endometrioid lesions of the female genital tract: CD10 is a characteristic marker of morular metaplasia

PURPOSE

To analyze immunohistochemically morules in endometrioid lesions to show that CD10 is a sensitive marker for morular metaplasia.

EXPERIMENTAL DESIGN

Immunohistochemical analysis of 53 instances of morular metaplasia comprising 1 cyclic endometrium and 52 endometrioid lesions associated with focal glandular complexity corresponding to 9 polyps, 4 atypical polypoid adenomyomas, 24 complex endometrial hyperplasias (18 with and 6 without atypia), 12 grade 1 endometrioid adenocarcinomas in early clinical stages of both uterus and ovary, and three ovarian adenofibromas. Immunohistochemistry in paraffin sections was done for CD10, beta-catenin, estrogen and progesterone receptors, and cytokeratins 5-6, 7, 8, 13, 18, 19, 20, and 34beta-E12.

RESULTS

Morules were negative for estrogen and progesterone receptors and had beta-catenin-positive nuclei. Cytokeratins 8, 18, 19 were positive; cytokeratins 7 and 20 were negative; and cytokeratins 5-6, 13, and 34beta-E12 were weakly positive. All cases revealed strongly positive membranous CD10 staining in morules, which was absent in glands. CD10 positivity allowed easy identification of morules at low power in various types of surgical specimens and in curettings. CD10 also highlighted early morular metaplasia in glandular epithelium. In cases associated with squamous, keratinizing metaplasia, CD10 discriminated between both types of metaplasia.

CONCLUSIONS

CD10 staining represents a useful marker of morules in endometrioid neoplasms of the female genital tract, permitting identification of lesions usually associated with an attenuated malignancy. Considering the immunohistochemical and genetic similarities of morules in tumors of different organs, it is likely that this marker may be also useful to diagnose morular metaplasia in similar neoplasms of extragenital locations.