Epithelial inclusion in axillary lymph node associated with a breast carcinoma: report of a case with a review of the literature

Ductal Carcinoma Arising in a Squamous Epithelial Inclusion Cyst within an Axillary Lymph Node: A Challenging Nodal Metastasis

Introduction. Assessment of axillary lymph nodes in breast carcinoma is an important part of staging to guide appropriate clinical management. Lymph node inclusions of different types, including nevoid, squamous, and glandular, are rare but have been reported in multiple different anatomic locations including the axilla. These can result in diagnostic challenges and pose risks of misdiagnoses. Rarely, malignancies may arise intrinsic to otherwise incidental benign nodal inclusions. Case Presentation. We report a case of ductal carcinoma diagnosed within a squamous epithelial inclusion cyst within an axillary lymph node in a patient with pure ductal carcinoma in situ (DCIS) of the ipsilateral right breast. To our knowledge, this is the fifth report in the literature of breast carcinoma confirmed within an axillary inclusion in a patient with pure DCIS. Evaluation of the primary DCIS and lymph node inclusions, by routine and immunohistochemical stains, was performed for assessment. Discussion. The presence of lymph node inclusions can pose a challenge in assessment of benignity and malignancy, on frozen and permanent histologic sections. Pathologists should carefully evaluate lymph node inclusions to ensure that intrinsic malignancies are not missed within rare otherwise benign appearing incidental epithelial rests.

Sentinel Lymph Node Involvement by Epithelial Inclusions Mimicking Metastatic Carcinoma: A Diagnostic Pitfall

BACKGROUND An epithelial inclusion cyst within a lymph node denotes a heterotopic phenomenon. Nodal epithelial inclusion cysts have been reported in a variety of anatomical locations including pelvic, abdominal, mediastinal, and axillary regions. While nodal melanocytic nevus (also known as nevus cell aggregates) is the most common heterotopic phenomena involving the axillary lymph nodes, the presence of benign epithelial inclusion cysts in axillary lymph nodes is a rare but well-reported finding. Such documentation is in part due to assessment of sentinel lymph nodes in breast cancer becoming standard of care. These epithelial inclusion cysts offer a diagnostic pitfall in evaluation of sentinel lymph node in the setting of breast carcinoma. They also complicate assessment of sentinel lymph node during intraoperative frozen sections analysis. CASE REPORT We report a case of co-existent of benign squamous-type and glandular-type epithelial inclusions cysts in 2 sentinel lymph nodes in a patient with grade III invasive ductal carcinoma involving the left breast. There have been at least 4 cases reported in literature in which benign epithelial inclusion cysts in sentinel lymph nodes were first mistakenly diagnosed as metastatic carcinoma both during intraoperative frozen section analysis and during review of permanent sections. The missed diagnosis could potentially occur intraoperatively during frozen section sentinel lymph node analysis secondarily due to lack of availability of the primary tumor for comparison and inability to use immunohistochemical stains. CONCLUSIONS Pathologists should be aware of this pitfall especially in frozen section analysis of sentinel lymph node to avoid misdiagnosis and its associated potential grave consequences.

Axillary Lymph Node Inclusions

Lymph node inclusions can occur in axillary lymph nodes, where they can mimic metastatic breast carcinoma. This article provides an overview of epithelial and nonepithelial lymph node inclusions, including mammary-type glandular inclusions, Mullerian-type glandular inclusions, squamous inclusions, mixed glandular-squamous inclusions, and nodal nevi. The discussion emphasizes the histologic and immunophenotypic features and differential diagnoses of each entity.

Endocervicosis involving axillary lymph nodes: first case report

The occurence of Mullerian epithelial inclusions, especially endosalpingiosis, in pelvic and other subdiaphragmatic lymph nodes is well known. In contrast, Mullerian inclusions involving lymph nodes above the diaphragm is uncommon, although occasional cases of endosalpingiosis have been reported. We report a case of benign Mullerian inclusions of mucinous endocervical type (endocervicosis) coexistent with metastatic breast-infiltrating ductal carcinoma in 2 axillary lymph nodes. The inclusions exhibited diffuse positive staining with CK7, PAX8, CA125, and estrogen receptor and were WT1 negative. To our knowledge, this is the first report of endocervicosis involving supradiaphragmatic lymph nodes. Close morphologic examination and immunohistochemistry assists in distinguishing Mullerian inclusions from metastatic adenocarcinoma.

Benign Epithelial Inclusions in Peripancreatic Lymph Nodes

Benign epithelial inclusions are rarely found in peripancreatic lymph nodes and have not been studied by up-to-date immunohistochemistry. Here, we describe 2 cases of benign epithelial inclusions in the peripancreatic lymph nodes with discussion of differential diagnosis. The first case was a 2.2 cm lymph node from a 61-year-old woman with pancreatic ductal adenocarcinoma. The second case was a 4.3 cm lymph node from a 28-year-old man with distal common bile duct cholangiocarcioma. The epithelial inclusions in the first case consisted of several small squamous cell nests with central duct-like lumina. The lymph node from the second case showed convoluted cystic inclusions lined by a single layer of bland cuboidal epithelium with scattered mucin-producing cells. We also conducted literature review on similar lesions and found that some lesions were associated with pancreatic hetertopia. It is imperative in clinical practice to distinguish these epithelial inclusions in the lymph nodes from tumor metastasis. A hypothetic connection of these benign epithelial inclusions in the peripancreatic lymph nodes to the enigmatic pancreatic lymphoepithelial cysts is suggested.

A Rapidly Enlarging Squamous Inclusion Cyst in an Axillary Lymph Node following Core Needle Biopsy

A 73-year-old woman was found to have a 1.7 cm axillary mass, for which a core needle biopsy was performed. The specimen revealed fragmented squamous epithelium surrounded by lymphoid tissue consistent with a squamous inclusion cyst in a lymph node, but a metastatic squamous cell carcinoma could not be excluded. Within one month, the lesion enlarged to 5 cm and was excised. Touch preparation cytology during intraoperative consultation displayed numerous single and sheets of atypical epithelioid cells with enlarged nuclei and occasional mitoses, suggesting a carcinoma. However, multinucleated giant cells and neutrophils in the background indicated reactive changes. We interpreted the touch preparation as atypical and recommended conservative surgical management. Permanent sections revealed a ruptured squamous inclusion cyst in a lymph node with extensive reactive changes. Retrospectively, the atypical epithelioid cells on touch preparation corresponded to reactive histiocytes. This is the first case report of a rapidly enlarging ruptured squamous inclusion cyst in an axillary lymph node following core needle biopsy. Our case demonstrates the diagnostic challenges related to a ruptured squamous inclusion cyst and serves to inform the readers to consider this lesion in the differential diagnosis for similar situations.

Epithelial inclusion cyst arising in an intramammary lymph node: case report with cytologic findings

The occurrence of epithelial inclusion cysts (EIC) in axillary lymph nodes is a rare but well recognized entity, arising either from direct implantation or from embryonal rests. Theoretically, EIC can occur in intramammary lymph nodes, but there has been only one prior report of such a lesion. Here, we describe a case of an EIC arising in an intramammary lymph node of a 37-year-old woman. This report focuses on the FNA cytologic features of this lesion and its differential diagnoses. On FNA, the EIC arising in an intramammary lymph node was characterized by mature lymphocytes, squamous epithelial cells, and keratinizing material. The presence of squamous cells can lead to the erroneous diagnosis of more common breast lesions, such as squamous cell carcinoma or metaplastic carcinoma. Contrary to these more sinister diagnoses, EIC arising in an intramammary lymph node is a benign condition. As this rare lesion sometimes mimics a neoplasm both clinically and radiographically, awareness of this entity is important to prevent over treatment.

Paracortical axillary sentinel lymph node ectopic breast tissue

Benign glandular inclusions in axillary lymph nodes are uncommon, and their presence in axillary sentinel lymph nodes is exceptionally rare. The possibility of over-staging due to misinterpretation of glandular inclusions as metastatic carcinoma is a concerning issue. We present a 54-year-old female with high grade ductal carcinoma in-situ undergoing simple mastectomy with sentinel lymph node biopsy. Permanent sections of the sentinel lymph node revealed scarce naked small glands without surrounding stroma scattered in the paracortex in the superficial level. Deeper levels showed glands spanning a much larger area (2mm), with bland ducts and tubules separated by abundant stroma. The myoepithelial layer was visible and was immunohistochemically confirmed. A final diagnosis of benign ectopic breast tissue within an axillary sentinel lymph node was rendered. Previous studies described axillary sentinel lymph nodes with glandular inclusions separated by stroma or subcapsular in location. It has been suggested that paracortical location and absence of stroma are characteristics of metastasis. As demonstrated in our report, benign inclusions may be paracortical and lack surrounding stroma. We recommend that glandular inclusions should be a diagnostic consideration for cases in which paracortically located naked glands do not histologically resemble the corresponding primary tumor.

Sclerosing adenosis in sentinel axillary lymph nodes from a patient with invasive ductal carcinoma: an unusual variant of benign glandular inclusions

Benign glandular inclusions in axillary lymph nodes are very rare events that have to be distinguished from metastatic carcinoma. We report an exceptional instance in which a patient with invasive ductal carcinoma had benign glandular inclusions in the form of sclerosing adenosis in 2 sentinel lymph nodes. The lymph nodes did not contain metastatic carcinoma. Immunohistochemical studies facilitated the correct diagnosis.

Ectopic breast tissue as a possible cause of false-positive axillary sentinel lymph node biopsies

Epithelial inclusions representing ectopic breast tissue are uncommonly seen in axillary lymph nodes. The extensive histopathologic examination of axillary sentinel lymph nodes of patients with breast carcinoma may increase the chances to encounter tiny foci of ectopic breast tissue, which may be misinterpreted as (micro)metastatic disease and lead to unwarranted completion of axillary dissection and to inaccurate staging and improper adjuvant treatments for the patients. Here we report on seven cases of ectopic breast tissue in axillary sentinel lymph nodes. In three cases there were coexistent micrometastases, and in the remaining cases the ectopic tissue was not associated with metastatic disease. The ectopic breast tissue showed remarkably varied morphologic features, including apocrine metaplasia and proliferative changes indistinguishable from those occurring in sclerosing adenosis and florid epithelial hyperplasia of the breast. A peripheral layer of myoepithelial cells was consistently detected in the ectopic glands and ducts. Besides awareness and purely morphologic criteria, a false-positive identification of these inclusions as metastatic carcinoma may be avoided by the use of immunohistochemical reactions for the localization of specific markers of the myoepithelial cell component, which is associated with the ectopic breast tissue.

Benign heterotopic epithelial inclusions in axillary lymph nodes. Histological and immunohistochemical patterns

Benign heterotopic epithelial inclusions in axillary lymph nodes are an extremely rare condition that must be differentiated from metastatic carcinoma. We describe 2 histologically different examples of benign epithelial inclusions in nonsentinel axillary lymph nodes, each with an unusual clinical presentation.