Illustration of chameleon blending into medical textbook page, representing a rare tumor mimicking a common disease.

Rare Tumor Mimics Metastasis: A Diagnostic Puzzle

Mira Elwood in Health & Wellness December 2025 • 4 min read.

"Unraveling the case of sebaceous lymphadenoma and its clinical masquerade"

In the realm of medical mysteries, rare conditions can often present diagnostic challenges. Sebaceous lymphadenoma (SL), a benign tumor primarily affecting the parotid gland, is one such entity. While its association with other malignancies is recognized, its ability to mimic metastatic disease can lead to clinical dilemmas.

A recent case highlights this diagnostic complexity. An elderly male patient, undergoing chemotherapy for a mixed testicular germ cell tumor, developed a swelling clinically suggestive of a metastatic lymph node. However, the true culprit was revealed to be a sebaceous lymphadenoma.

This article delves into the intricacies of this case, emphasizing the importance of tissue diagnosis in differentiating sebaceous lymphadenoma from metastatic lesions. By understanding the clinical presentation, diagnostic workup, and histological features of SL, clinicians can ensure appropriate management and avoid potential misdiagnosis.

The Case: A Masquerade Unveiled

Illustration of chameleon blending into medical textbook page, representing a rare tumor mimicking a common disease.

A 50-year-old male, previously treated for a mixed germ cell tumor of the testicle, presented with a new cervical swelling. Initial suspicion pointed towards metastatic disease, a common concern in patients with a history of cancer. A CT scan revealed infiltrates in the base of the lung, raising concerns about bleomycin toxicity from his chemotherapy regimen.

Fine needle aspiration cytology (FNAC) of the swelling was performed, revealing macrophages, neutrophils, lymphocytes, and foreign body giant cells within a haemorrhagic background. Although special stains ruled out fungal or bacterial infections, a diagnosis of necrotizing lymphadenitis with giant cell reaction was suggested. However, the clinical suspicion for metastasis remained high, prompting an excisional biopsy.

The excised node displayed unique characteristics:

A yellowish-white color with a soft to firm consistency.
Numerous tiny cysts visible on the cut surface.
Microscopic examination revealed ducts arranged in cribriform and tubular patterns.
Sheets of foamy macrophages and foreign-body type giant cells.
Presence of sebaceous glands, foci of squamous metaplasia, and cystically dilated lymphatic spaces.

These findings prompted a differential diagnosis including mucoepidermoid carcinoma and Warthin's tumor. Cytological smear review aided in differentiating macrophages from oncocytes and intermediate epithelial cells. Oil red O stain confirmed fat presence in sebaceous glands and lymphatic spaces, while immunohistochemistry further characterized the cell populations. Ultimately, the constellation of features led to the diagnosis of sebaceous lymphadenoma of the parotid gland.

Key Takeaways: A Lesson in Diagnostic Vigilance

This case underscores the importance of considering rare benign entities in the differential diagnosis of suspected metastatic disease. Sebaceous lymphadenoma, while uncommon, can clinically and radiologically mimic metastatic lesions, leading to potential misdiagnosis and inappropriate management.

Accurate tissue diagnosis, including careful histological examination, special stains, and immunohistochemistry, is crucial for distinguishing SL from other entities, particularly metastatic carcinoma. Cytological review can also be valuable in differentiating macrophages from other cell types.

By increasing awareness of the diverse presentations of sebaceous lymphadenoma and employing comprehensive diagnostic approaches, clinicians can ensure optimal patient care and avoid unnecessary interventions.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1097/pat.0b013e328355aefb, Alternate LINK

Title: Sebaceous Lymphadenoma Of The Parotid Gland: A Rare Lesion Masquerading As A Metastatic Node In An Elderly Male Patient With Mixed Testicular Germ Cell Tumour On Chemotherapy

Subject: Pathology and Forensic Medicine

Journal: Pathology

Publisher: Elsevier BV

Authors: Rajesh Nachiappa Ganesh, Chaithra Gv, Ankit Jain, Sajini Elizabeth Jacob, Neelaiah Siddaraju

Published: 2012-08-01

Everything You Need To Know

What is a sebaceous lymphadenoma, and why is it significant in this context?

A sebaceous lymphadenoma (SL) is a benign tumor, meaning it's not cancerous, that primarily affects the parotid gland, which is a salivary gland located near the ear. Its significance lies in its ability to mimic more serious conditions, particularly metastatic disease. This can lead to misdiagnosis and unnecessary treatments, underscoring the importance of accurate diagnosis.

What was the patient's condition and what were the initial findings that led to the diagnostic challenge?

In this scenario, a 50-year-old male, previously treated for a mixed germ cell tumor of the testicle, presented with a cervical swelling. Initial investigations, including a CT scan, suggested the possibility of metastatic disease. The patient had a history of testicular cancer and was undergoing chemotherapy. The presence of a swelling that resembled a metastatic lymph node, alongside other findings, led to a suspicion of cancer spread. However, further examination showed the presence of a sebaceous lymphadenoma and not a metastasis of cancer cells.

What makes the diagnosis of sebaceous lymphadenoma so challenging?

The challenges arise because sebaceous lymphadenoma (SL) can present clinically and radiologically like metastatic lesions. For instance, the swelling caused by the SL might be mistaken for a cancerous lymph node. The article explains that the initial diagnostic workup, including Fine Needle Aspiration Cytology (FNAC), was inconclusive. The excisional biopsy of the node was crucial in revealing the unique histological features of the sebaceous lymphadenoma, such as its characteristic microscopic patterns and the presence of sebaceous glands. Without these detailed examinations, the condition could have been misinterpreted, and the patient might have received incorrect treatment.

What specific features of the sebaceous lymphadenoma helped in its diagnosis?

The excisional biopsy revealed the unique characteristics of sebaceous lymphadenoma. It had a yellowish-white color with a soft to firm consistency. The cut surface showed numerous tiny cysts. Microscopic examination revealed ducts arranged in cribriform and tubular patterns, sheets of foamy macrophages and foreign-body type giant cells, sebaceous glands, foci of squamous metaplasia, and cystically dilated lymphatic spaces. Cytological smear review differentiated macrophages from oncocytes and intermediate epithelial cells. Oil red O stain confirmed fat presence, while immunohistochemistry further characterized the cell populations. These findings helped to accurately identify and differentiate the sebaceous lymphadenoma from the suspected metastatic lesion.

What is the key takeaway from this case regarding the diagnosis of this kind of condition?

This case emphasizes the importance of considering rare conditions like sebaceous lymphadenoma in the differential diagnosis. If clinicians only focus on common conditions, they risk misdiagnosing a patient. Accurate tissue diagnosis is critical. The specific diagnostic techniques such as FNAC, excisional biopsy, cytological smear review, Oil red O stain, and immunohistochemistry were vital in distinguishing the sebaceous lymphadenoma from a metastatic lesion and ensuring the patient received the correct treatment. This is a lesson in diagnostic vigilance and the need for a comprehensive evaluation.