Histopathological study of 26 rare skin adnexal tumours over 5 years--a diagnostic dilemma!
Skin adnexal tumors (SATs) are those neoplasms that differentiate toward or arise from pilosebaceous unit, eccrine sweat glands or apocrine sweat glands, and these tumors are classified into four groups that exhibit histologic features analogous to hair follicles, sebaceous glands, and eccrine glands.  These tumors are derived from multipotential undifferentiated cells present within the epidermis or its appendageal structures and the histologic features of a tumor are related to the activation of molecular pathways responsible for forming the mature adnexal structure.  SATs are rare in Indian subcontinent and hence pose difficulty in diagnosis as they may histopathologically look like more common skin malignancies in this region. Several studies on SATs have been carried out in Western countries but very few in this region.
Most of the benign SATs are present as asymptomatic papules or nodules and are often difficult to diagnose clinically however anatomic location, number, and distribution of lesions provide important clue and no change required.  However, histopathology and immunohistochemistry may help in confirmation of the diagnosis.[R] This study was therefore undertaken to analyze adnexal tumors of the skin for their morphological, clinical, and histological features and to group them using the International Classification of World Health Organization (2006).
Materials and Methods
This study includes the cases from January 2010 to June 2015. A total of 26 cases were included in this study, which were reported by the histopathology sections of the Department of Pathology, Hi-Tech Medical College and Hospital Bhubaneswar, Odisha. The clinicopathological data were taken from the record office for the given period. The histopathological examination was carried out on formalin-fixed tissues and paraffin embedded blocks were made. Hematoxylin and eosin stained sections were examined and few special stains such as PAS and reticulin were performed wherever required. However in our laboratory setup, histochemical staining for enzymes such as alkaline phosphatase, phosphorylase, succinic dehydrogenase, indoxyl esterase, and acid phosphatase was not available; they were not performed.
In this study, 92.31% (24/26) were benign and 7.69% (2/26) were malignant adnexal tumors. The sebaceous gland tumors constituted the largest group (42.31% 11/26) cases followed by the sweat gland tumor (34.62%, 9/26) cases and hair follicle tumor (23.10%, 6/26) cases [Tables 1-3].
The male: female ratio was 1.16:1. Tumors were observed in all age groups ranging from 11 to 85 years. However, the highest incidence was observed in the age group of 40-49 years (11/26). The most commonly affected body part was head and neck regions (61.53%, 16/26) followed by trunk (15.38%, 4/26). Eccrine poroma, sebaceous hyperplasia, and pilomatrixoma were the most common benign tumors and two sebaceous carcinoma were the only two malignant tumors seen.
The sweat gland tumors are comprised of chondroid syringoma, eccrine poroma, nodular hidradenoma, and syringocystadenoma papilliferum [Figure 1]. Sebaceous gland tumors are comprised of sebaceous adenoma and sebaceous carcinoma. The hair follicle tumors are comprised of trichofolliculoma (sebaceous), pilomatricoma, and dilated pore of Winer (Figures 2-5). Among the malignant tumors, sebaceous carcinoma was the only malignant tumor observed and constituted 7.69% (2/26).
Incidence of benign tumors was more as compared to malignant cases. Sebaceous gland tumors were most common. Head and neck were the most common sites. Males and females were almost equally affected and most commonly between 40 and 49 years of age. Radhika et al.,  Reddy et al.  and Samaila  who reported 77.14%, 69.41%, and 88.5% benign and 29.63%, 30.59%, and 11.5% malignant lesions respectively, these were similar results to our study as in this study 92.31% (24/26) tumors were benign and 7.69% (2/26) were malignant. Nair  observed that sweat gland tumors are the most common followed by hair follicle tumors. However, this study showed that the most common tumors were sebaceous, followed by sweat gland tumors. Radhika et al.  and Samaila  observed that sweat gland tumors are the most common SATs followed by sebaceous gland tumors which are then followed by tumors of hair follicle. Male: female ratio as observed by Nair  and Saha et al.  was 1: 2.3 and 1: 1.88, respectively. Radhika et al. also observed that majority of the patients are third decade and females outnumbered males.  However, this study showed male: female ratio of 1.16:1. Saha et al. observed the mean age of onset of SATs was 24.15 [+ or -] 8.44. Nair  observed that the most common age group of presentation was 11-20 years, however in this study, the common age group of presentation was 40-49 years. Samalia  observed that 46% lesions were located in head and neck regions which were also seen in our study. Song et al. observed that pilomatricoma was the most common benign tumor followed by dermoid cyst followed by steatocystoma multiplex, syringoma, and trichilemmal cyst.  Radhika et al. observed that the most common benign tumor is nodular hidradenoma followed by sebaceous naevus.  In this study, most common tumors were eccrine poroma, sebaceous hyperplasia, and pilomatrixoma.
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Strength of this study was that special stains and IHC were carried out to confirm the diagnosis whenever required. Limitations are that in spite of studying cases for 5 years we could still only get 26 tumors of which only two were malignant.
In Indian population, an overall incidence of skin adnexal tumors is very low. The incidence of benign skin adnexal tumors is more as compared to the malignant ones. Most of the malignant tumors occur in older age group usually more than 50 years of age. However, benign tumors show a wide age variation. Skin adnexal tumors can occur anywhere in the body; however head and neck regions constitute the most common sites. Majority of the tumors can be classified into different subgroups on the basis of light microscopy alone. Skin adnexal tumors showing sebaceous gland differentiation are seen more frequently. In our institutional study, eccrine poroma is the most common tumor with sweat gland differentiation, whereas pilomatrixoma is the most common type of hair follicle tumor. Among the tumors with sebaceous differentiation, sebaceous hyperplasia and sebaceous carcinoma (meibomian carcinoma) are the most common.
[1.] Ahmed TSS, Priore JD, Seykora JT. Tumors of epidermal appendages. In: Lever's Histopathology of the Skin, 9th edn, Elder DE, Elenitsas R, Johnson BL, Murphy GF (Eds.). Philadelphia, PA: Lippincott Williams & Wilkins, 2005. pp. 867-8.
[2.] Stantaylor R, Perone JB, Kaddu S, Kerl H. Appendage tumors and hamartomas of the skin. In: Fitzpatrick's Dermatology in General Medicine, Wolff K, Goldsmith L, Katz S, Gilchrest BA, Paller AS, Leffell DJ (Eds.). New York, NY: McGraw Hill, 2008. pp. 1068-1087.
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Sadaf Alam, Misbah Lateefa, Raghumani Mohanty
Department of Pathology, Hi-Tech Medical College and Hospital, Bhubaneswar, Odisha, India.
Correspondence to: Sadaf Alam, E-mail: firstname.lastname@example.org
Received January 31, 2016. Accepted March 11, 2016
Table 1: Adnexal tumors according to the type of differentiation Type of differentiation No. of cases % Sebaceous gland tumors 11 42.31 Sweat gland tumors 9 34.62 Hair follicle tumors 6 23.10 Total 26 100 Table 2: The site and sex distribution of observed adnexal tumors Site of tumor Male Female Total % Head and Neck 9 7 16 61.53 Trunk 2 2 4 15.38 Other areas 3 3 6 22.09 Total 14 12 26 100 Table 3: Age-wise distribution of tumors Age group (in years) Tumors 1-9 10-19 20-29 30-39 40-49 Sebaceous gland tumors Sebaceous hyperplasia 3 Sebaceous adenoma 2 2 Nevus sebaceous 1 Sebaceous carcinoma Sweat gland tumors Chondroid syringoma 1 Eccrine poroma 1 1 Nodular hidradenoma 1 Syringocystadenoma papilliferum 1 Eccrine Syringofibroadenoma 1 1 Hair follicle tumors Pilomatricoma 1 1 Trichofolliculoma (Sebaceous) 1 1 Dilated port of Winer 1 Age group (in years) Tumors 50-59 60-69 >70 Sebaceous gland tumors Sebaceous hyperplasia 1 Sebaceous adenoma Nevus sebaceous Sebaceous carcinoma 1 1 Sweat gland tumors Chondroid syringoma Eccrine poroma 1 Nodular hidradenoma 1 Syringocystadenoma papilliferum Eccrine Syringofibroadenoma Hair follicle tumors Pilomatricoma 1 Trichofolliculoma (Sebaceous) Dilated port of Winer
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|Title Annotation:||Research Article|
|Author:||Alam, Sadaf; Lateefa, Misbah; Mohanty, Raghumani|
|Publication:||International Journal of Medical Science and Public Health|
|Date:||Oct 1, 2016|
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