Mc. Sicari et al., Photoinduced dermal pigmentation in patients taking tricyclic antidepressants: Histology, electron microscopy, and energy dispersive spectroscopy, J AM ACAD D, 40(2), 1999, pp. 290-293
Two patients had been taking long term tricyclic antidepressant therapy. Ea
ch developed a blue to slate-gray hyperpigmentation in sun-exposed areas. O
n histologic examination there were refractile golden brown granules free i
n the dermis along collagen bundles. Similar pigment was present in macroph
ages and along the basement membrane zone. The granules stained for melanin
, but not for iron, and were bleached by the permanganate method. Electron
microscopy showed varying size and shaped electron-dense granules within ly
sosomes and free in the dermis, which, in unstained sections, showed a less
dense peripheral halo. This peripheral halo was also evident on light micr
oscopy. Energy dispersive spectroscopy showed these granules to be rich in
copper and sulfur (elements present in tyrosinase and pheomelanin, respecti
vely). We believe that this represents a drug-melanosome complex, which is
most likely caused by chronic photoactivation.