Axillary Lymph Node Inclusions

Benign Islet Cells Within Peripancreatic Lymph Nodes: A Potential Diagnostic Pitfall

The presence of epithelial cells within lymph node parenchyma is typically indicative of a metastatic malignancy. However, there are rare instances in which non-neoplastic epithelial or epithelioid cells may be found within lymph nodes, either due to aberrant embryologic migration, mechanical displacement, or physiological trafficking. These can potentially lead to serious potential diagnostic pitfalls, as when such situations are encountered by surgical pathologists, there is substantial risk of overdiagnosing these as metastatic malignancy. Herein, we describe 2 cases of benign pancreatic islet cells within peripancreatic lymph nodes, and underscore the potential for misdiagnosis of this phenomenon as foci of metastatic well-differentiated neuroendocrine tumor. The benign nature of these intranodal islet cells was supported by: (1) the absence of a well-differentiated neuroendocrine tumor in the entirely submitted concomitant pancreatic resection specimen and (2) the presence of an admixture of insulin and glucagon expressing cells by immunohistochemistry in a distribution characteristic of non-neoplastic pancreatic islets. Both cases were incidental microscopic findings in pancreatic resections for intraductal papillary mucinous neoplasms that were previously biopsied and showed associated microscopic areas of fibrosis and chronic pancreatitis and thus this phenomenon may be related to mechanical displacement from prior injury and/or biopsy.

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.

Metastatic Mammary Carcinoma Presenting as a Large Cystic Axillary Mass: A Report of an Unusual Case

The differential diagnosis of cystic axillary masses is broad and includes intranodal lesions. Cystic metastatic tumor deposits are rare, and have been reported in a few tumor types, most commonly in the head and neck region, but rarely described with metastatic mammary carcinoma. We report a case of a 61-year-old female who presented with a large right axillary mass. Imaging studies revealed a cystic axillary mass and ipsilateral breast mass. She was managed with breast conservation surgery and axillary dissection for invasive ductal carcinoma, no special type, Nottingham grade 2 (21 mm). One of nine lymph nodes contained a cystic nodal deposit (52 mm), which resembled a benign inclusion cyst. Oncotype DX recurrence score for the primary tumor was low (8), conferring a low risk of disease recurrence despite the large size of the nodal metastatic deposit. A cystic pattern of metastatic mammary carcinoma is rare and important to recognize for accurate staging and management decisions.

Update on sentinel node pathology in breast cancer

Pathologic examination of the sentinel lymph nodes (SLNs) in patients with breast cancer has been impacted by the publication of practicing changing trials over the last decade. With evidence from the ACOSOG Z0011 trial to suggest that there is no significant benefit to axillary lymph node dissection (ALND) in early-stage breast cancer patients with up to 2 positive SLNs, the rate of ALND, and in turn, intraoperative evaluation of SLNs has significantly decreased. It is of limited clinical significance to pursue multiple levels and cytokeratin immunohistochemistry to detect occult small metastases, such as isolated tumor cells and micrometastases, in this setting. Patients treated with neoadjuvant therapy, who represent a population with more extensive disease and aggressive tumor biology, were not included in Z0011 and similar trials, and thus, the evidence cannot be extrapolated to them. Recent trials have supported the safety and accuracy of sentinel lymph node biopsy (SLNB) in these patients when clinically node negative at the time of surgery. ALND remains the standard of care for any amount of residual disease in the SLNs and intraoperative evaluation of SLNs is still of value for real time surgical decision making. Given the potential prognostic significance of residual small metastases in treated lymph nodes, as well as the decreased false negative rate with the use of cytokeratin immunohistochemistry (IHC), it may be reasonable to maintain a low threshold for the use of cytokeratin IHC in post-neoadjuvant cases. Further recommendations for patients treated with neoadjuvant therapy await outcomes data from ongoing clinical trials. This review will provide an evidence-based discussion of best practices in SLN evaluation.

Endocervicosis in an Intramammary Lymph Node

Benign müllerian inclusions are frequently encountered within infra-diaphragmatic locations such as pelvic lymph nodes, bladder, cervix and vagina. Supra-diaphragmatic müllerian inclusions, especially endocervicosis, are exceedingly rare. We report a case of endocervicosis within an intramammary lymph node in a 49-year-old woman. To the best of our knowledge, this is the second reported case.

Neoadjuvant Therapy in Breast Cancer: Histologic Changes and Clinical Implications

Cytotoxic or endocrine therapy before surgery (neoadjuvant) for breast cancer has become standard of care, affording the opportunity to assess and quantify response in the subsequent resection specimen. Correlation with radiology, cassette mapping, and histologic review with a semi-quantitative reporting system such as residual cancer burden (RCB) provides important prognostic data that may guide further therapy. The tumor bed should be identified histologically, often as a collagenized zone devoid of normal breast epithelium, with increased vasculature. Identification of residual treated carcinoma may require careful high power examination, as residual tumor cells may be small and dyscohesive; features are widely variable and include hyperchromatic small, large, or multiple nuclei with clear, foamy, or eosinophilic cytoplasm. Calculation of RCB requires residual carcinoma span in 2 dimensions, estimated carcinoma cellularity (% area), number of involved lymph nodes, and span of largest nodal carcinoma. These RCB parameters may differ from AJCC staging measurements, which depend on only contiguous carcinoma in breast and lymph nodes.

Endosalpingiosis Is Negative for GATA3

CONTEXT.—

Endosalpingiosis is a benign Müllerian inclusion that can mimic metastatic low-grade mammary carcinoma, particularly when encountered in axillary lymph nodes excised for breast cancer staging. Immunohistochemistry can be useful in histologically ambiguous cases, and a targeted immunopanel should include a marker of gynecologic tract origin and a marker of mammary origin. GATA3 is a sensitive immunomarker for breast carcinoma, but the immunoreactivity of GATA3 in endosalpingiosis has not been systematically evaluated.

OBJECTIVE.—

To evaluate whether GATA3 immunohistochemistry could be used to differentiate endosalpingiosis from metastatic mammary carcinoma.

DESIGN.—

Whole slide sections of 15 cases of endosalpingiosis involving nonneoplastic tissues were subjected to GATA3 immunohistochemistry. Nuclear GATA3 labeling was scored as percentage and intensity labeling, with any labeling considered positive; GATA3 labeling was recorded in all cells present in the sections.

RESULTS.—

Half (47%, n = 7 of 15) of the endosalpingiosis cases involved lymph nodes (2 axillary, 5 pelvic) and half (53%, n = 8 of 15) involved pelvic organs or soft tissue (3 myometrial, 2 paratubal, 2 periadnexal soft tissue, and 1 pelvic sidewall). GATA3 immunohistochemistry was negative in all cases of endosalpingiosis, with intact, positive control labeling in lymphocytes. The benign fallopian tube epithelium present on the sections of paratubal endosalpingiosis displayed focal (<5%), weak labeling for GATA3, specifically within the ciliated and secretory cells.

CONCLUSIONS.—

These findings support the diagnostic utility of GATA3 immunohistochemistry and its use in a targeted immunopanel to resolve the differential diagnosis of metastatic low-grade mammary carcinoma (GATA3+) and nodal endosalpingiosis (GATA3-).

Epithelium Involving Bilateral Axillary Lymph Nodes: Metastasis, Misplaced, or Mullerian!

During breast cancer staging, histological evaluation of axillary sentinel lymph nodes (SLN) is usually straightforward. However, the exact characterization of a small epithelial deposit in an SLN can be challenging, especially during the frozen section examination. We report the first case of endosalpingiosis involving bilateral axillary lymph nodes. We review published literature on axillary endosalpingiosis and discuss the differential diagnosis of small epithelial deposits in an axillary SLN. Pathologists should consider benign epithelial rests and displaced epithelium as differential diagnoses for the microscopic epithelial nodal deposit, especially during the frozen section examination.

The first case of gland inclusion in an intrapulmonary lymph node: a mimic of metastasis

Background

Lymph node inclusions are foci of ectopic tissue in lymph nodes, which were reported in different areas of the body. However, inclusions in the mediastinal lymph node are rare. Here, we report the first case of glandular inclusion within the parenchyma of the intrapulmonary lymph node in a patient with primary lung adenocarcinoma.

Case presentation

A computed tomography (CT) scan showed a solid pulmonary nodule in the right upper lobe in a 44-year-old man. After a fine needle aspiration biopsy diagnosis of adenocarcinoma, lobectomy and lymph dissection were performed. Histological sections of the lung demonstrated a papillary predominant adenocarcinoma and one intrapulmonary lymph node, which displayed glandular inclusion occupying the node parenchyma. The gland inclusion was very similar to metastasis, but was formed by two layers of epithelial cells, and the abluminal cells were positive for P63, P40, and CK5/6. The patient has remained alive without recurrence and metastasis at the last follow-up before publication.

Conclusions

It is very important to correctly diagnose a lymph node inclusion for proper clinical management.