Eccrine spiradenoma in knee.

Eccrine spiradenoma is an uncommon benign adnexal tumor of the eccrine sweat glands. Although it can occur at any age, it is most common in young adults without any sex predilection. Malignant transformation is rare, presenting as rapid increase in size of a long-standing lesion. Here, we report a case of eccrine spiradenoma in a 35-year-old man who presented with swelling over the right knee, with cytological atypia but no recurrence until date.

What was known?

Common site of presentation is upper half of the ventral half of the body

Eccrine spiradenoma is an uncommon benign adenexal tumor of eccrine sweat gland (malignant transformation is rare).

Introduction

Eccrine spiradenoma, also known as spiradenoma, is an uncommon benign tumor of sweat glands, first described by Kersting and Helwing in 1956.[1] It usually presents as a single skin tumor, showing typical histological features. It mainly occurs in young adults, equally among both sexes. The lesion is mostly solitary and painful and consists of a firm, rounded, bluish, dermal nodule. The nodule usually develops on the head, neck, and back of the trunk. A frequent symptom of this neoplasm is spontaneous pain or tenderness on palpation. Malignant transformation is rare, but has been reported and described in literature previously. We here report a case of eccrine spiradenoma of the right knee in a 35-year-old man with features of cytological atypia.

Case Report

A 35-year-old man presented with a history of small painful nodule over his right knee for past 2.5 years. Family history and past medical history were insignificant. The lesion began as a small papule, which slowly increased in size over time. The lesion was tender on firm pressure, adherent to superficial dermis, and clinically well demarcated. Routine haematological and biochemical investigations were normal. Mantoux test was negative. The lesion was excised and dispatched for histological examination. Gross examination of the resected specimen showed a 5 × 4-cm, pink-blue nodular lesion with adherent normal looking skin [Figures 1 and 2]. The specimen was fixed in 10% neutral buffered formaldehyde solution, tissue was processed and stained with hematoxylin and eosin stain. Microscopic examination revealed several sharply delineated, basophilic nodules in the dermis without any connection with the epidermis [Figure 3]. At higher magnifications, the tumor mass was observed to be composed of two distinct cell population the first type being small, dark basaloid cells located at the periphery of the lesion and the second type being large, pale cells having large vesicular nuclei with pale cytoplasm at the center of the lesion. Parts of the tumor also showed some cytological atypia [Figure 4]. Patient was on follow-up, and, until the time of writing this article, no recurrence has been observed.

Figure 1

Gross examination of the resected specimen showing pink-blue nodular lesion with adherent normal looking skin

Figure 2

Cut surface of the specimen of eccrine spiroadenoma

Figure 3

several sharply delineated, basophilic nodules in the dermis without any connection with the epidermis

Figure 4

H and E stained section of eccrine spiroadernoma showing two cell population small basoloid cell at the periphery and large pale cell at the center, few cell also show atypia, ×400

Discussion

Eccrine spiradenoma classically presents in 20-40 years of age. Most presentations of eccrine spiradenoma are solitary, comprising >97% of cases. The incidence of eccrine spiradenoma is somewhat similar in men and women.[2] Malignant transformation is rare, and it usually occurs 20-30 years after the initial lesion detection with a mortality rate of 39% if left untreated.[2]

Eccrine spiradenoma usually appears as a solitary nodule, but multiple lesions may also be present. The epidermis that covers the lesion may be normal in color or pinkish and ulcerated.[3] Eccrine spiradenoma belongs to the group of the painful tumors of the skin. This vast group includes glomus tumor, blue rubber bleb naevus, leiomyoma, eccrine spiradenoma, neuroma, dermatofibroma, angiolipoma, neurilemmoma, endometrioma, glomangioma, and granular cell tumor.[4] Microscopically, the tumor is composed of two types of cells in a well-delineated nodular pattern: Larger, paler cells grouping around the lumina and smaller, darker cells forming the periphery of the tumor.[5] Cystic spaces or small, tubular structures may also be present.[6] Malignant changes usually appear in long-standing tumors and is clinically revealed by a rapidly enlarging tumor mass.[67] Spiradenoma may be associated with other skin adenexal tumors namely trichoepitheliomas and cylindromas (in the form of Brooke–Spiegler syndrome), chondroid syringoma, and apocrine adenoma. Eccrine spiradenoma may present as multiple segmental eccrine spiradenoma, vascular eccrine spiradenoma, carcinosarcomatous ex eccrine spiradenoma, and eccrine spiradenoma with neurofibromatosis.[289101112]

The method of treatment is surgical excision and because recurrences have been reported, close follow-up of the patient is required.

Conclusion

We thus conclude that such tumor needs to be treated early to prevent malignant changes and recurrence probably in long-standing cases. In the case presented here, some cytological atypia that could have later progressed to malignancy was observed. To avoid repeat surgery (if malignancy is found histologically), wider resection of the lesion was performed at the first opportunity. Fortunately, in this case, until date, there has been no recurrence.

What is new?

Uncommon site of presentation of eccrine spiradenoma (i.e., knee)

Atypia (which may progress to frank malignancy) has been observed in this case.