Introduction
Skin appendageal tumours (SATs) are those neoplasms that arise from pilosebaceous units, apocrine, or eccrine sweat glands. These tumours have both benign and malignant counterparts and some exhibit mixed differentiation.1 They clinically present as papules, nodules, and tumours. The correct diagnosis has important implications, as they might be markers for syndromes associated with internal malignancies. 2 Malignant skin appendageal tumours are uncommon, aggressive, and bear a poor clinical outcome. Therefore, proper diagnosis of SATs is important for therapeutic and prognostic reasons.
In this study, we have discussed the incidence, clinical features, gross and microscopic features, and the differentiating features between benign and malignant SATs of patients who attended our dermatology OPD.
Case Report
This is a case series spanning over a period of one and a half years, from January 2021 to July 2022, at Hitech Medical College, Rourkela. Clinico-pathological characteristics of all benign and malignant tumours were studied.
This is a case series spanning over a period of one and a half years, from January 2021 to July 2022, at Hitech Medical College, Rourkela. Clinico-pathological characteristics of all benign and malignant tumours were studied. Out of twenty-four thousand, two hundred twenty-four new patients attended the OPD, of whom 30 (0.123%) were suspected to have appendageal tumors. The clinical diagnosis of all these cases were dermoid cyst, haemangioma, sebaceous cyst, and nevus. The clinical features, age, sex, gross, and histopathological diagnosis are given in [Table 1].
Table 1
The clinical features, age, sex, gross and histopathological diagnosis
Table 2
Tumour site and histopathology
|
S.No |
Tumour |
Site & clinical details in our study |
Histopathology |
|
1 |
Pilomatrixoma |
single case in the scalp measuring 1.7 x 1.2 x 1.0 cm in size |
Biphasic pattern of keratinized ghost cells surrounded by variable numbers of basaloid cells. [Figure 7] |
|
2 |
Proliferating pilar tumour |
Single case in scalp measuring 4.5 x 4.0 x 4.0 cm |
multiple lobules of squamous epithelium; typical abrupt trichelemmalkeratinisation in the centre [Figure 4] |
|
3 |
Hidradenoma |
3 cases on different sites (leg,skin& scalp) Circumscribed, non encapsulated., masses that lie in the dermis and subcutaneous tissue |
Cells with clear and eosinophilic cytoplasm. Usually solid; but they can be cystic. Ductal differentiation can be seen. [ Figure 8] |
|
4 |
Trichoepithelioma |
Two cases both cases on scalp measuring 2cm |
Symmetric lesion: mixture of epithelial elements ranging from hair germs associated with papillary mesenchymal bodies and small horn cysts.[Figure 1] |
|
5 |
Malignant adnexal tumor of hair follicle origin |
Single case on scalp measuring 3cm, surface ulceration and asymmetry was present |
Numerous papillary projections lined by cuboidal cells, cellular pleomorphism, frequent mitosis and foci of necrosis which were seen in our case signify the malignant features. The deep resected margin was free.[Figure 6] |
|
6 |
Apocrine Hidrocystoma |
One case reported on back measuring 3cm |
Cystic spaces lined by double layer of epithelial cells: outer layer of myoepithelial cells & inner layer of tall columnar cells.[Figure 9] |
|
7 |
Steatocystoma multiplex |
One case reported on back measuring 0.7cm |
Cyst with lining similar to corrugated cuticle of sebaceous ducts with sebaceous glands. [Figure 2] |
|
8 |
Malignant adnexal tumour of eccrine origin |
Multiple swelling present on face largest measuring 5cm with clinical signs of malignant transformation like rapid growth, ulceration, bleeding and pain were present |
Nests separated by hyalinised stroma around cell nests, loss of peripheral palisading of cells, bimorphic population of cells, cellular pleomorphism, frequent mitosis and foci of necrosis which were seen in our case signify the malignant features. The tumour was seen extending up to the deep resected margin [Figure 3] |
|
9 |
Hidradenoma papilliferum |
Single swelling measuring 2cm present in perineal area |
An adenoma with apocrine differentiation located in the dermis with tubular and cystic structures with papillae projecting in to them. [Figure 5] |
Figure 1
H & E: Trichoepithelioma: Nests of basaloid cells, horn cysts and mesenchymal bodies (H&E X10)
Figure 2
H & E: Steatocystoma: Dermis showing intricately folded cyst wall lined by layers of epithelial cells with a thick cuticular layer and flattened sebaceous gland (H&E X10)
Figure 3
H & E: Malignant adenexal tumour: Tumour arranged in nests separated by hyalinised stroma around cell nests, loss of peripheral palisading of cells, bimorphic population of cells, cellular pleomorphism, frequent mitosis and foci of necrosis which were seen in our case signify the malignant features. (H&E X10)
Figure 4
H & E: Proliferating pilar tumour: multiple lobules of squamous epithelium with typical abrupt trichilemmal keratinisation in the centre (H&E X10)
Figure 5
H & E: Hidradenoma papilliferum: tumour shows numerous papillary projections lined by cylindrical and cuboidal cells with active decapitation secretion. (H & E X 10)
Figure 6
H & E: Malignant adenexal tumour: tumour shows numerous papillary projections lined by cuboidal cells, cellular pleomorphism, frequent mitosis and foci of necrosis which were seen in our case signify the malignant features. (H&E X10)
Figure 8
H & E: Hidradenoma: The tumor shows two types of cells one with eosinophilic cytoplasm and other with clear cytoplasm (H&E X10)
Figure 9
H & E: Apocrine hidrocystoma: The dermis contains the lesion with multi loculation lined by a row of columnar secretory cells with focal papillary projections (H&E X10)
In 12 patients, a diagnosis of epidermoid cyst was offered; three cases turned out to be xanthomas and three cases were dermoid cysts. In 12 cases out of 30 biopsied, it was confirmed as an appendageal tumour. There were 11 cases with the tumours situated in the head and neck region, and one case is noted in the vault. They presented as nodules and tumours. Six tumours were more than 3 cm in size, and one case with a diameter greater than 5 cm was diagnosed as a malignant adnexal tumour of eccrine origin. The rest of the five tumours measured less than 3 cm. Hair follicular differentiation tumours were found in 5 cases (41%).Eccrine and apocrine tumours were found in 5 cases (41%). Malignant tumours were two of the types that constitute 16% of appendageal tumors. One was showing eccrine differentiation, and the other had multiple swellings on the face and nasolabial area exhibiting sebaceous differentiation. A syndromic association was suspected, and patients were referred to a higher centre for treatment. The morphology of both cases is described in [Table 2].
Discussion
The SATs include a big and diverse category of neoplasms and histopathology is considered the gold standard in the diagnosis.3, 4 The inidence of SATs in our study is 0.123 percent. The male female ratio is 1:3. The benign-to-malignant ratio is 5:1. [Table 2] lists the benign and malignant tumours that were reported in our case series. Two malignant tumours were reported in our study. The present study shows nodular hidradenoma as the predominant tumour similar to Radhika K et al.,5 and trichoepithelioma 6 is the next common tumour. Trichoepitheliomas were the most common tumours in other studies.7 The general characteristics that distinguish benign from malignant SATs are symmetrical lesions, homogenous collections of epithelial cells, and the absence of necrosis, atypia, and mitosis as characteristics of benign tumours.8
Conclusion
Histopathology is considered the gold standard for the diagnosis of SAT. Before removing them, it is crucial to search for malignant characteristics, as despite their rarity, malignant SATs are aggressive. More cases sent for biopsy reduces the chance of missing a malignant case.
Authorship
All the authors have contributed enough towards this publication to justify authorship criteria.
