Volume 21Number 4, Part 1October 1989

peated intermittent courses of topical sulconazoletherapy.

We thank the other investigators, each of whomenrolled up to nine patients with T. rubrum in this mul­ticenter study: William Crutcher, MD, Napa, California;Susan Elliott, MD, Greenbrae, California; Ronald Ka­han, MD, Norwalk, Connecticut; Lawrence Charles Pa­rish, MD, Philadelphia, Pennsylvania; Lynn A. Drake,MD, Atlanta, Georgia; Stanley Spatz, MD, Hallandale,Florida; Stanley Cullen, MD, Gainesville, Florida; Ken­neth Arndt, MD, Boston, Massachusetts; Robert Auer­bach, MD, New Haven, Connecticut; and Alan Shalita,MD, Brooklyn, New York.

REFERENCES1. Tanenbaum L, Anderson C, Rosenberg MJ, et aI. Sul­

conazole nitrate 1.0 percent cream: a comparison with

Sulconazole in moccasin-type tinea pedis

miconazole in the treatment of tinea pedis and tineacruris/corporis. Cutis 1982;30:105-18.

2. Lassus A, Forsstr5m S, Sala O. A double-blind comparisonof sulconazale nitrate 1% cream with clotrimazole 1%cream in the treatment of dermatophytoses. Br J Dermatol1983;108:195-8.

3. Lassus A, Forsstrom S. A double-blind parallel study com­paring sulconazole with econazole in the treatment of der­matophytoses. Mykosen 1984;27:592-8.

4. Woscoff A, Carabeli S. Treatment of tinea pedis with sul­conazole nitrate 1%creamor miconazole nitrate 2% cream.Curr Ther Res 1986;39:753-7.

5. Jones HE. Cell-mediated immunity in the immunopatho­genesis of dermatophytosis. Acta Derm Venereal [suppl](Stockh) 1986;121:73-83.

Tanning-bed lentigines: Ultrastructural andhistopathologic featuresJonathan R. Salisbury, MRCPath,' Hywel Williams, MRCP,b andAnthony W. P. du Vivier, FRCpb London, England

The development of unusual melanocytic lesions after exposure to UVA tanning beds hasbeen reported recently. We studied one such case with the use of light and electronmicroscopy and found the appearance similar to the lentigines that may occur afterpsoralen photochemotherapy. Histologically, some melanocytes showed mild nuclearatypia. Ultrastructural examination showed features similar to those of other forms oflentigo. (J AM ACAD DERMATOL 1989;21:689-93.)

UVA-induced melanocytic lesions that devel­oped after use of a home tanning bed (also knownas a sun bed) without concomitant psoralen admin­istration were recently described. 1 These lesions canbe distinguished from simple freckles and solarlentigines both clinically and histologically but bearsome similarities to the PUVA-induced lentigines.

From the Department of Morbid Anatomy, King's College School ofMedicine,' and the Department of Dermatology, King's CollegeHospital," Denmark Hill.

Accepted for publication Oct. 10, 1988.

Reprint requests: J. R. Salisbury, MRCPath, Department of MorbidAnatomy, King's College School of Medicine, Denmark Hill,London SE5 8RX, United Kingdom.

16/1/14926

In this report we describe the pathologic features ofa case of tanning-bed lentigines with emphasis onthe ultrastructural findings.

CASE REPORT

A 35-year-old white woman had numerous lentigines,predominantly on the anterior part of the legs (Fig. 1).The lentigines were variable in size and unevenlypigmented with irregular borders. The lesions appearedabruptly during a period of intense tanning-bed use in 50half-hour sessions during a 10-week period. The specificwavelengths that this patient received are not known.Although tanning beds are designed to emit UVAradiation (315 to 400 nm), many are contaminated bysmall but significant amounts of UVB radiation (280 to315 nm). The patient had type III skin, and she was

689

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Fig. 1. Densely scattered lesions of irregular shape and pigmentation on front of shinsafter use of tanning bed.

Fig. 2. Photomicrograph of biopsy specimen of lentigo shows densely pigmented kerati­nocytes in lower layers of epidermis and moderate increase in melanocytes. The nuclei ofsome melanocytes show mildly atypical features. (Hematoxylin-eosin stain; X20.)

taking a low-dose combined oral contraceptive. Thelesions continued to enlarge and coalesce for 18 monthsdespite strict avoidance of ultraviolet radiation. Two skinbiopsy specimens were taken 6 months apart for histo­pathologic examination, and a portion of each wasprocessed for electron microscopy.

Histopathologic findings

In the first skin biopsy specimen the basal cell andprickle cell keratinocytes were heavily pigmented butdid not show loss of normal orientation or alterations incellular or nuclear size and shape. Melanocytes wereincreased within the basal layer, and a small number ofupwardly migrating melanocytes within the epidermiswas present (Fig. 2). Some melanocytes showed mildlyatypical cytologic features; they were large and pos-

sessed angular and hyperchromatic nuclei. Neithermitoses nor giant melanosomes were found. The papil­lary and reticular layers of the dermis appeared normalexcept for a mild, perivascular, chronic inflammatoryinfiltrate in the papillary dermis. Dermal melanophageswere not present. The second specimen showed similarchanges, although both the amount of pigment withinkeratinocytes and the number of melanocytes wereslightly reduced.

Ultrastructural findings

Electron microscopy showed that the basal cell andprickle cell keratinocytes were heavily laden with largecompound melanosomes (melanosome complexes),some of which contained more than 50 discernible singlemelanosomes, together with small amounts of fine,

Volume 21Number 4, Part 1October 1989 Tanning-bed lentigines 691

Fig. 3. Low-power electron micrograph of dermoepidermal junction and lower layers ofepidenQis. Keratinocytes are heavily laden with melanosomes. Pale-stained melanocytes arepresent in basal epidermal layer. (Uranyl acetate-lead citrate stain.)

granular material (Figs. 3 and 4). In some keratinocytesthese compound melanosomes were so numerous thatthey indented or displaced the nucleus and obscured thecytoplasmic tonofilaments (Fig. 4). Almost all melano­somes within the keratinocytes were present in com­pound melanosomes, but relatively large and predomi­nantly single melanosomes, as described in the keratino­cytes of PUVA lentigines,2 were not present. Abnormalor granular forms of melanosomes were not seen. Apartfrom the findings noted above, the keratinocytes ap­peared normal.

Most basal layer melanocytes contained moderatenumbers of stage IV melanosomes, although somecontained only a few. A few stage III meJanosomes werenoted, but earlier stages were not seen. Melanocytenuclei were large and contained one or two prominentnucleoli; a few melanocytes were binuclear. Mitochon­dria and endoplasmic reticula were scanty, but mostmelanocytes possessed abundant dendrites containingmany melanosomes (Fig. 5). Some melanocytes con­tained one or two melanosome complexes of up to 30single melanosomes grouped together in the cytoplasm.Others contained increased numbers of single melano­somes, apparently related to the base of the dendrites, inparticular regions of the cell (Fig. 5).

ColJagen fibers were disrupted in the papillary der-

mis, although light microscopy had not revealed solarelastosis. A granular degeneration of elastic fibers wasalso seen.

DISCUSSION

The histopathologic characteristics and ultra­structure of the various forms of lentigo have beenwell studied. A simple lentigo has an increasednumber of melanocytes in the basal layer withincreased melanin in both melanocytes and basalcell keratinocytes. Some of the rete ridges arebranched and slightly elongated.

In senile (solar) lentigo, the rete ridges areelongated, and there is a proliferation of heavilypigmented basaloid cells, which form buds andstrands.) The melanocyte density is increased,although this may not be apparent,4 and a fewmelanocytes are located above the basal layer. Thekeratinocytes contain increased numbers of com­pound melanosomes that are generally larger thannormal. Some attain considerable size and consistof hundreds of single melanosomes.s

Melanocytes in PUVA lentigines are increasedin number and size, and, unlike solar lentigines,

692 Salisbury et al.

Journal of theAmerican Academy of

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Fig. 4. Electron micrograph of keratinocyte in prickle cell layer from typical lentigo onlower part of leg. Many compound melanosomes are visible. (Uranyl acetate-lead citratestain.)

Fig. 5. Electron micrograph of melanocyte in basal layer of epidermis. Numerousme1anosome-filled dendrites are seen between keratinocytes. Increased numbers of simplemelanosomes in melanocyte appear to have aggregated in one area. (Uranyl acetate-leadcitrate stain).

Volume 21Number 4, Part 1October 1989

they may be cytologically atypical6•7 and occasion­ally binuclear.8 The keratinocytes are heavily pig­mented and may contain large compound melano­somes. Ultrastructural studies of PUVA lentigineshave shown the numbers of melanosomes, mito­chondria, endoplasmic reticula, and dendrites ofthe me1anocytes to be increased. Large numbers oflipid droplets and of lysosome-melanosome com­plexes are also found and are considered to bepathologic features. The surrounding keratinocytesare laden with melanosomes9• 10 and contain bothlarge single melanosomes and larger individualmelanosomes within compound melanosomes. 2

One of six cases described by Nakagawa et al.2 alsoshowed marked melanosome pleomorphism, inclu­ding abnormal forms.

Tanning-bed lentigines are presumably a veryrare hazard of tanning bed use, and we are awareof only one other reported case. I The long-termimplications with regard to potential dysplastic nevior melanoma are unknown, but patient follow­up is clearly a sensible precaution. Histologically,tanning-bed lentigines resemble PUVA lentiginesinsofar as melanocyte density is increased andsome melanocytes show mild nuclear atypia. Ultra­violet light is known to lead to a general increase inmelanocyte density and to the development of morestage IV melanosomes than normal in the skin ofwhite persons. II Ultrastructurally, the appearanceof this type of lentigo is similar to that reportedlyobserved in other forms of lentigo and the densityof compound melanosomes within keratinocytes,although striking, is similar to that reported insolar- and PUVA-induced lentigines and nevi.s.7

The presence of melanosome complexes within

Tanning-bed lentigines 693

melanocytes is unusual, because small compoundmelanosomes are found in normal melanocytes ononly rare occasions. II Such occurrences, however,are probably of little significance. Small melana­some complexes are frequently observed in themelanocytes of PUVA lentigines and occasionallyin solar lentigines.2

REFERENCES

I. Jones SK, Moseley H, MacKie RM. UVA-inducedmelanocytic lesions. Br J Dermatol 1987;117:111-5.

2. Nakagawa H, Rhodes AR, Momtaz-T K, et al. Morpho­logic alterations of epidermal melanocytes and melano­somes in PUVA lentigines: a comparative ultrastructuralinvestigation of lentigines induced by PUVA and sunlight.J Invest Dermatol 1984;82: IOJ -7.

3. Mehregan AI-I. Lentigo senilis and its evolution. J InvestDcrmatol 1975;65:429-33.

4. Hodgson C. Senile lentigo. Arch Dermatol 1963;87:197­207.

5. Montagna W, Hu F, Carlisle K. A reinvestigation of solarlentigines. Arch Dermatol 1980;116:1151-4.

6. Gschnait F, Wolff K, Honigsmann H, et al. Long-termphotochemotherapy: histopathological and immunofluo­rescence observations in 243 patients. Br .T Dermatol1980;103:11-22.

7. Rhodes AR, Harrist TJ, Momtaz-T K. The PUVA­induced pigmented macule: a lentiginous proliferation oflarge, sometimes cytologically atypical, melanocytes.J AM ACAD DERMATOL 1983;9:47-58.

8. Abel EA, Reid H, Wood C, et al. PUVA-inducedmelanocytic atypia: is it confined to PUVA lentigines?J AM ACAD DERMATOL 1985;13:761-8.

9. Konrad K, Gschnait F, Wolff K. Ultrastructure ofpoikiloderma-like pigmentary changes after repeatedexperimental PUVA-overdosage. J Cutan Pathol 1977;4:219-20.

10. Kanerva L, Lauharanta J, Niemi K-M, et al. Persistentashen-grey maculae and freckles induced by long-termPUVA treatment. Dermatologica 1983;166:281-6.

11. Ghadially FN. Ultrastructural pathology of the cell andmatrix. 2nd ed. London: Butterworth, 1982:599-622.

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