Primary adrenal teratomas are exceedingly rare germ cell tumors originating from totipotent cells and are composed of tissues from all three germ layers (ectoderm, mesoderm, endoderm). We report here a 53-year-old male who presented with abdominal pain for 2 months. Ultrasound and CT scan revealed a multiloculated cystic lesion (10.5 × 8.5 cm) in the right adrenal gland. Adrenal function tests were normal, indicating a non-functional tumor. Laparoscopic complete excision of the gland was performed. Gross examination revealed a lobulated cystic mass. On microscopy, a mature teratoma was diagnosed, without immature neuroepithelium or somatic malignancy. Primary mature adrenal teratoma, which is an extremely rare retroperitoneal tumor, may present as an incidental adrenal mass. Histopathological evaluation remains indispensable for definitive diagnosis and exclusion of immature or malignant elements. Surgical excision is both diagnostic and curative. Adrenal teratomas, though rare, should be the differential diagnosis of adrenal masses.

Highlights:

• Primary adrenal teratomas are exceedingly rare and may present as a retroperitoneal mass.
• The patient presented with abdominal pain. 
• Ultrasound and CT scan were helpful in the initial suspicion of cystic lesions. 
• Histopathology is diagnostic of a mature teratoma and is important to rule out an immature component.
• The tumor was completely resected, remained asymptomatic, and showed no evidence of recurrence. 

Teratoma is a type of germ cell tumor originating from peripheral pluripotent stem cells, composed of tissues from all three germ cell layers, i.e., the ectoderm, mesoderm, and endoderm tissues [1]. Interestingly, teratomas are exceedingly rare and uncommon tumors, with an estimated incidence rate of only 0.9 per 100,000 in the general population [2]. They are categorized into subtypes by the extent of maturation, with mature teratomas being the most common subtype [3].

It can occur at any age, and in adults, it is mainly located in the gonads (testes or ovaries). Retroperitoneal teratomas are rare, accounting for only 4% of all primary teratomas [1]. It is even more exceptional for these tumors to be located within the adrenal gland. Primary adrenal teratomas represent an exceptionally rare subset of this already uncommon category [2]. As a consequence, only a limited number of cases have been documented and published in the medical literature, underscoring the distinctive and elusive nature of these tumors [2].

Here, we report a rare case involving a mature teratoma in the right adrenal gland of a 53-year-old adult male.

A 53-year-old male presented with complaints of abdominal pain for 2 months and was found to have a left adrenal complex cyst on ultrasonography of the abdomen. He was admitted to the hospital for adrenal hormone examination, which showed normal adrenal function tests. Contrast computed tomography (CT) of the adrenal gland showed a peripherally enhancing multiloculated cystic lesion in the left adrenal gland. An adrenal endothelial cyst was kept in the differential diagnosis. The mass was surgically excised via laparoscope with complete excision of the right-sided retroperitoneal adrenal mass.  Grossly, the adrenal mass was lobulated with a cut surface showing predominantly adipose tissue, interspersed grey-white firm areas, and a cystic area with a calcified wall. Histologically, the representative sections revealed derivatives of all three germ layers, including mature epidermal structures, glandular epithelium, bone, cartilage, skeletal muscle fibers, adipose tissue, seromucinous glands, as well as multinucleate giant cells, pigment-laden macrophages, and areas of necrosis. No areas of immature neuroepithelium or somatic malignancy were seen. (Figure. 1, A-D). This case report has been reported in line with the SCARE criteria [4].

Figure 1: Microscopic examination, H&E stain, 10X: Reveals derivatives of all three germ cell layers, including mature epidermal structures, glandular epithelium (A), bone, cartilage (B), adipose tissue, and seromucinous glands (C), skeletal muscle fibers (D).

Teratoma is a germ cell tumor derived from totipotent cells, which comprise tissues originating from more than one germ cell layer, usually all three, and giving rise to different tissues such as skin, muscle, nerve, fat, and tooth structures [5]. Although in adults they predominantly occur in the gonads, about 15% of teratomas occur in extragonadal sites [6]. Extragonadal teratomas often occur in midline structures, such as the anterior mediastinum, retroperitoneum, sacrococcygeal region, pineal gland, and the suprasellar region1Primary extragonadal teratomas in retroperitoneal locations are extremely rare and account for only 4% of primary teratomas and 1%–11% of all primary tumors in the retroperitoneal region [7]. Highlighting the rarity of adrenal gland teratomas, only 39 cases have been reported in the past 30 years [8].

The close anatomic association of the adrenal cortex with the urogenital apparatus and its embryological development from coelomic epithelium make it a possible site of development of teratoma [9]. Retroperitoneal mature cystic teratomas exhibit an interesting pattern of incidence, with two distinct peaks observed in infancy and early adulthood [3]. They seem to be more common in women than in men, and the left suprarenal region appears to be the predominant site for retroperitoneal cystic teratomas [10]. Most adrenal teratomas are unilateral, with only one documented case of bilateral involvement [11].

The retroperitoneum provides ample space for these tumors to grow, resulting in a typically substantial size upon presentation [12]. Adrenal mature teratomas are generally non-functional, and the tumor exhibits latent growth. During the early stages, the tumor will be nearly asymptomatic. Later, as it increases in size, the patient might experience pressure-associated symptoms like abdominal discomfort, back pain, nausea, vomiting, urinary retention, intestinal obstruction, and sometimes swelling of the lower limbs and genitals due to lymphatic obstruction [13].

Diagnostic imaging is crucial for the diagnosis of adrenal teratomas, as laboratory findings are typically nonspecific. Modalities such as plain radiography, abdominal ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) of the abdomen are useful for diagnosing teratomas [14]. Because of the heterogeneity of fat content and density, differential diagnosis among adrenal myelolipoma, angiomyolipoma, liposarcoma, pheochromocytoma, or malignant tumors is usually considered. Other differential diagnoses of retroperitoneal teratomas include ovarian tumors, renal cysts, adrenal tumors, sarcomas, retroperitoneal fibromas, hemangiomas, xanthogranuloma, enlarged lymph nodes, and perirenal masses [15].

A definitive diagnosis of adrenal teratoma, however, requires histopathological evaluation, which is the gold standard. Histologically, teratomas contain elements derived from more than one germ cell layer i.e. endoderm, mesoderm and ectoderm and different tissues such as fat, hair, skin and teeth can be seen. These are further categorized into mature and immature teratomas. Mature teratomas are benign and show differentiated tissues. Immature teratoma is composed of undeveloped/ undifferentiated tissues and is classified as benign, possibly malignant, or frankly malignant.8 A group of exceptionally rare teratomas known as teratomas with malignant transformation tend to undergo malignant transformation and have an increased tendency to metastasize. Malignant transformation usually occurs in stratified squamous epithelial components. Somatic malignancies such as carcinoma, sarcoma, and leukemias may also occur within a teratoma [16].

Surgical intervention remains a cornerstone of management, providing both diagnostic clarity and therapeutic benefits [3]. The goal is the complete removal of the tumor without damaging adjacent structures and to relieve clinical symptoms and prevent malignant transformation [7]. Complete surgical resection followed by close surveillance is the treatment of choice for mature teratomas and is essential for establishing a definitive diagnosis. Laparoscopic surgery has emerged as the primary treatment modality for benign adrenal tumors, surpassing open surgery. However, in the case of an immature teratoma, adjuvant therapy, such as chemotherapy, radiotherapy, or concurrent chemoradiotherapy, may be required following complete resection of the primary tumor [3]. A close post-operative follow-up is recommended. Lastly, the five-year survival rate is almost 100 %, which indicates an excellent prognosis after the surgical resection [17].

Primary mature adrenal teratoma represents a rare diagnostic entity within the spectrum of adrenal and retroperitoneal tumors. Its nonspecific clinical presentation and overlapping radiologic features often pose diagnostic challenges. Histopathological evaluation remains indispensable for definitive diagnosis and exclusion of immature or malignant elements. Surgical excision is both diagnostic and curative, with favorable outcomes in mature lesions. Increased documentation of such rare cases is essential to strengthen existing literature, refine differential diagnoses of adrenal masses, and guide optimal clinical management.

Abbreviations

CT: Computed Tomography

MRI: magnetic resonance imaging

SCARE: Surgical Case Report

H&E stain: Hematoxylin and eosin stain 

Declarations

Ethical Approval and consent to participate.

This study has been exempted from ethical approval by our institutional research committee (xxxx). 

Consent for publication: 

The patient provided written informed consent for publication and the use of case details, including images.

Availability of data and material: Not applicable.

Competing interests: The authors have no conflicts of interest to declare that are relevant to the content of this article.

Funding: No funds, grants, or other support were received.

Authors' contributions: xxxx.

Acknowledgements: None.