Pigmented Poroma of the Lower Eyelid: A Case Report and Literature Review

Background

A poroma is a benign neoplasm that can be of eccrine or apocrine origin and is histogenetically associated with the intraepidermal (acrosyringial) part of the excretory ducts of the eccrine sweat glands. The disease code according to ICD-10 is D23.9. Occurrence of this tumor on the eyelid is rather rare [1]. Poroma usually occurs in older patients, without a gender predominance [2,3] and the exact pathogenesis of this lesion is unknown [4]. After radical removal, the prognosis of any form of poroma is favorable [5]. It can occur together with other skin lesions (eg, verruca plantaris and acral lentiginous melanoma), creating combined pathologies that are difficult to diagnose [6,7].

Recent research has revealed a genetic background to this disease, showing that about 85% of poroma cases are related with the following gene fusions: YAP1-MAML2, MAML2-YAP1, YAP1-NUTM1, and WWTR1-NUTM1, which are a consequence of intrachromosomal inversions and translocations [8–10]. NUT and transcriptional repressor GATA binding 1 (TRPS1) are potential molecular markers of poroma [11,12]. Ultraviolet radiation does not seem to be a key pathogenic factor in poroma development. Merkel cell polyomavirus (MCPyV) infection, existing malignancies, and organ transplantation history are important risk factors [9,13].

Our case is interesting because the neoplasm was localized on the lower eyelid at a young age (12–14 years). Other unusual characteristics of this clinical case were pigmentation, unpleasant smell, and the intense growth of the poroma, which coincided with significant acute stress because she was living in the area of military actions in Ukraine.

Case Report

TREATMENT:

The removal of the tumor was carried out with the method of radio frequency wave, followed by histopathological examination using routine staining with hematoxylin and eosin (H&E). The healing proceeded without complications, within 10 days, by secondary intension. The patient was satisfied with the treatment and the aesthetic result (Figure 1E). No recurrence was reported within 9 months after surgery.

HISTOPATHOLOGY:

Histopathological examination revealed a poroma. The main observation was the proliferation of epidermal cells with the formation of squamous bodies (Figure 2). Among the epidermal population, there were groups of cells with a small amount of eosinophilic cytoplasm and rounded hyperchromic nuclei (poroid cells). Moreover, multiple corneal pseudocysts and single mucin-filled ductal structures were observed in a series of sections. The morphological architecture was consistent with eccrine poroma (ICD-O code 8409/0) with features of traumatization. However, the subtype of poroma (eccrine/ apocrine) could not be determined. The clinical differential diagnostic was done with the seborrheic keratoma and no additional immunostaining was performed due to the lack of malignancy features.

Discussion

Poromas can arise on any skin surface, but those arising from eccrine tissue are most commonly found on the palms, soles, and scalp. That is why poroma on the eyelid is a rare pathology [1]. Other recently reported rare localizations of eccrine poroma are right thigh (lesion diagnosed in 74-year-old Chinese woman) and right lateral foot (lesion diagnosed in 82-year-old African American man) [14,15].

The development of benign poroma is based on simple hyperplasia of epidermal cells of the sweat gland, associated with exposure to an unknown trigger without visual damage to the nearby skin. The pathological process is generally slowly progressing [5].

Poroma is usually non-pigmented (17% are pigmented variants) and underdiagnosed due to confusion with other pigmented tumors. Most frequently, poroma is confused clinically with basal cell carcinoma, squamous cell carcinoma, and cutaneous melanoma [16].

To date, there are only 9 reported cases of this tumor on the eyelids. We included the most important information about all reported clinical cases of the poroma (located in the peri-orbital zone) in Table 1, which compares the cases according to specific parameters.

We found some essential differences in our case of eyelid poroma in comparison to the generally accepted literature data, which may be important in facilitating diagnosis of this rare disease.

According to literature, all reported poromas occurred at an older age (mostly over 60 years) [2,17–24]. Thus, we show for the first time that the tumor can also appear in early adolescence (the patient was 12–14 years old). In our case, the lesion did not grow during the first 15 years and then very rapid tumor growth was observed – it doubled in size during about 6 months. This active growth coincided with the patient’s acute stress related to the war in Ukraine. Currently, the direct cause of such expansive growth is not known, but there is evidence that stress hormones promote the occurrence and development of tumors through various mechanisms [25].

Moreover, it should be noted that contrary to the information about the absence of sex predominance, our analysis (Table 1, together with our case) revealed that poroma of the eyelid was diagnosed more commonly in men than in women, with a male-to-female ratio 7: 3.

Finally, all diagnosed poromas were painless and only 2 cases (including ours) had a symptom of a bad smell. However, unlike the patient reported by Ahuja et al, in our case, there was no secretion from the tumor or the nearest eccrine ductus [17]. Thus, we hypothesized that the tumor became too big and as a result, was adhesive to the skin. Consequently, it caused difficulties in skin breathing and hygiene, resulting in bad smell.

It is also very important to differentiate benign tumors from malignant ones. The fundamental difference between these types of tumors is the absence of atypia in the structure of the benign ones. In our case, no abnormal cells or asymmetric architecture (suggestive of the malignant nature of the lesion) were observed, so there was no need to perform additional immunostaining. However, in more complex and uncertain cases, immunostaining for carcinoembryonic antigen (CAE) is crucial to differentiate between benign and malignant lesions [26].

Conclusions

Reported clinical case of eccrine poroma of the eyelid makes an important contribution to the diagnosis of skin cancer, not only due to its rare localization, but also because of its special features. Our case is the first that appeared during adolescence. It also stands out from others with its unusual pigmentation, the presence of an unpleasant smell, and extremely fast growth, which can be related to the patient’s acute war-related psychological stress. There is a need to educate doctors of various specialties (including ophthalmologists) to make them aware that poroma may occur on the eyelids of patients of all ages. Specialists should also be familiar with its treatment, especially since it can be frequently confused with other benign and malignant tumors.