Case Report
A 40-year-old French male patient was referred to us with a 7-year
history of multiple pigmented macules on the trunk and extremities. The
patient had no history of diabetes mellitus or injections, including
steroids and insulin. No relevant clinical manifestations were observed
among his family members. Physical examination revealed multiple,
slightly depressed, and pigmented macules ranging from 1 to 3 cm in
diameter without hypertrichosis on the trunk and extremities
(Figure 1 ).
Histopathological examination demonstrated irregularly distributed,
bundled pale eosinophilic structures of various sizes with oval-shaped
nuclei in the upper dermis by hematoxylin and eosin staining
(Figure 2a ). There was no discernible increase in the number of
melanocytes in the epidermis or hair follicles. Masson trichrome
staining showed that the irregularly distributed and variously sized
bundled structures were less stained than collagen fibers in the dermis
(Figure 2b ). These findings collectively indicated an aberrant
proliferation of mature smooth muscle in the upper dermis. Based on
these findings, the diagnosis of SMH was made. The patient was followed
for 6 months, during which time there was no change in the cutaneous
manifestations.