Title: ADENOLIPOMA OF THE SKIN Authors: C. DEL AGUA, F FELIPO Affiliations: Deparment of Pathology. Hospital General de Soria. Soria. Spain. celiadelagua@eresmas.com Citation: DOJ Editing/Review 10 mayo 2003 Abstract: Adenolipoma of the skin is an unusual variant of lipoma recently described by Hitchcock et al. characterized by the presence of normal eccrine sweat glands. We report a case and review the literature. A 45 year-old woman presented with a painless nodule, slowly-growing in thigh, clinically considered as lipoma. Microscopically, it was composed by an adipose tissue proliferation with single eccrine secretory coil and associated duct in the peripheria and in the center of the nodules. This benign lesion has been called adenolipoma due to the presence of adipose tissue and eccrine glands. Probably, it is only a histological curiosity in which the eccrine glands are entrapped by the adipose proliferation. Adenolipoma of the skin is a distinc lesion that can occur in the dermis or subcutaneous tissue. Body: I: Introduction Adenolipoma of the skin is an unusual variant of lipoma recently described by Hitchcock et al. (1( characterized by the presence of normal eccrine sweat glands. We report a case and review the literature. I: Case report A 45 year-old woman presented with a painless nodule, slowly-growing in her thigh. At clinical examination they were considered as lipoma and the lesion was removed. Grossly it showed a soft, yellow, lobulated tissue measured 2.5 cm in greatest diameter. Figures 1 and 2: 1.jpg, 2.jpg Fig 1: ECRINE GLANDS SITUATED WITHIN FATTY PROLIFERATION. Fig 2: HIGH POWER VIEW OF ECCRINE DUCT. Microscopically, the nodule was composed by an adipose tissue proliferation with distinc lobulation within the tumor. Single eccrine secretory coil with an associated duct were seen in the peripheria and in the center of the nodule. A well developed capsule was identified. Aside from the expansion of the coil by adipose tissue, no architectural nor cytologic alteration was seen in the eccrine glands. I: Discussion In 1993 Hitchcock et al. (1(, described, a lipoma of the skin with epithelial component that was named "adenolipoma of the skin". Since, two series have been reported, the first by Hitchcock et al. (1( with 9 cases and the second by Ait-Ourhrouil et al. (2( with 11 cases. Other descriptions of this lesion are limited to case report (3(. The most frequent location is the thigh, followed by the shoulder region, chest and arm. The diameter of the lesion varies from 1 to 6 cm. Clinically, all lesions was presented as a solitary, painless, slowly-growing tumor. Most often they were diagnosed on clinical examination as lipomas and less frecuently as skin tags or neurofibromas. The average age is 50 years (range from 25 to 75). They were on gross examination defined, yellow and soft lobulated tumor. Histologically, a well-developed capsule was identified in most of the lesions. There were composed by lobulated adipose tissue with larger and more prominent lobules than those of normal subcutaneous adipose tissue. Well-differenciated eccrine glands and ducts are seen inside the neoplastic adipose tissue, without fibrous stroma. In the cases in which a relation to the dermis could be assessed, the glands were situated more deeply than normal eccrine glands. Ait-Ourhrouil et al. (2( measured the distance between dermis and eccrine glands in normal skin and in adenolipomas, and they reported that mean distance was 40( in normal skin (range from 0, for intradermal glands, to 750 (, for hipodermical glands) while it was 15 mm in adenolipomas (range from 6.70 to 20 mm). The clinical data, the enlarged lobules of fatty tissue and the abnormal presence of eccrine glands help diagnose adenolipoma. However, can exist problems to its diagnose in fragmented specimens due to impossibility to asses the location of eccrine glands. Another source of pitfall is the peripherical location of the eccrine glands in the specimens which difficult to assess whether glands were contained in the tumor or were merely adjacent normal structures. Serial sectioning of lesions could confirm the presence of glandular component without possibility to underestimate this lesion. The normal anatomic variability in the location of eccrine glands suggest the possibility of dermal, subcutaneous or combined locations for adenolipomas. The differential diagnosis includes the common lipoma and its variants, the lipomatous variant of eccrine angiomatous hamartoma (4( and nevus lipomatous cutaneous superficialis (5(. The adenolipoma has a similar appearance than the common lipoma. The mean diameter of adenolipoma is smaller than that of common lipomas but the age at time of resection and the tendency to spare distal sites are shared features with it. A subcutaneous lipoma may compress the dermis and produce a similar appearance to the adenolipoma. However, displacement of the eccrine glands rather than incorporation into the lesion suggest the subcutaneous lipoma. Eccrine angiomatous hamartoma is generally a single lesion present on an extremity at birth, that show increased numbers of eccrine structures and numerous capillary channels surrounding or intermingled with the eccrine structures. Its rare lipomatous variant may also contain fatty tissue. Nevus lipomatous superficialis usually presents as multiple papules or nodules linearly distributed on the buttock or hip. The lesion may be present at birth or may be begin in infancy. Solitary lesion have been diagnoses but it seems be preferable to regard them as polypoid fibrolipomas. Microscopically, there are presence the groups of fat cells among the collagen bundles of the dermis in variable amount. Aside from that, the dermis may be enterely normal, but the density of the collagen bundles, the number of fibroblasts , and the vascularity are greater than the normal skin. Perivascular inflammation and abundant mast cells are seen. This lesion has been called adenolipoma by Hitchcock et al. (1( due to the presence of adipose tissue and eccrine glands, rejecting the term "adnexal fat pad lipoma" because of the absence of follicular, sebaceous or apocrine glands. To these authors the term lipoadenoma is not appropriate because this name implies a neoplastic proliferation of the eccrine glands and it is believed that the glands are entrapped and carried by the adipose proliferation rather than neoplastic. On the other hand, Ait-Ourhrouil et al. (2( suggested the name "perisudoral lipoma". They believe that this lesion develops from peripherical adipose tissue from eccrine glands and the term adenolipoma is consider inappropriate because the glands or ducts never show glandular proliferation component. We agree with Hitchcock et al. (1( and believe that the adenolipoma is a fatty tissue proliferation, which include and move the normal eccrine glands to the center of the nodule, rather than neoplastic. Although this lesion originates from the fat pad around the sweet coils we prefer the term adenolipoma because it does not suppose the presence of glandular proliferation component but a entrapped glandular component. References: 1- Hitchcock M, Hurt M, Santa Cruz D. Adenolipoma of the skin: A report of nine cases. J Am Acad Dermatol 1993; 29:82-85. 2- Ait-Ourhrouil M, Grosshans E. Le lipome pŽrisudoral. Ann Dermatol Venereol 1997: 124; 845-848. 3- Rongioletti F, Santa Cruz D. L«adŽnolipoma cutanŽ. Ann Dermatol Venereol 1997; 124: 855-856. 4- Donati P, Amantea A, Balus L. Eccrine angiomatous hamartoma: a lipomatous variant. J Cutan Pathol 1989; 16: 227-229. 5- Dotz W, Prioleau PG. Nevus lipomatous cutaneus superficialis: A light and electron microscopic study. Arch Dermatol 1984; 120:376.