We present two Japanese cases of involutional lipoatrophy. The first case is that of a 30-year-old woman, who first appeared at our hospital complaining of a localized, well-demarcated depression, approximately 3 × 4 cm in size, normal to slightly erythematous in coloration, on the lateral side of the left upper arm (Fig. 1a). The condition was asymptomatic, and she had noticed this anomaly a month prior to consultation. She received intramuscular injections of corticosteroids of unknown dosage at the affected site for the treatment of allergic rhinitis 4 months prior to her present consultation.
The second patient, a 23-year-old woman, appeared at our hospital complaining of a similar macule 4 × 4 cm in size, which she noticed several weeks prior to her most recent consultation. She had no history of injury or injection at the site before the development of the condition (Fig. 1b). She had been under treatment for atopic dermatitis since early childhood and was treated only with topical applications of white petrolatum containing 2% salicylic acid for the past several years.
In order to rule out the possibility of acquired partial lipodystrophy associated with localized scleroderma, lupus profundus and the other connective tissue diseases, a histological examination was performed for both patients. Histopathological analysis of the region exhibited a well-defined fat lobule composed of numerous small adipocytes (Fig. 1c) embedded in hyaline connective tissue. Edema and dilated capillaries were noticeable in the subcutaneous tissue surrounding the area. Inflammatory cells were not prominent, although mononuclear cells were observed in both patients. No epidermal change was seen in either patient.
Direct and indirect immunofluorescence studies revealed no deposits of immunoreactants in the skin of either patient. Immunohistochemical studies with the antibody against macrophage (anti-CD68 antigen; DAKO.) showed that positive cells were scattered around blood vessels and shrunken lipocytes in the subcutaneous tissues (Fig. 1d). Most of these cells in the fat lobules were also positive for mucin stains such as Alcian blue.
No abnormal findings came to light in the ordinary hematological and blood chemistry examinations of both patients. The autoantibody screening tests using antinuclear, anti-DNA, anticentromere, and anti-Scl-70 antibodies were negative in both patients.