THE JOURNAL OF INVESTIGATIVE DERMATOLOGY, 67 :285-287, 1976 Copyright © 1976 by The Williams & Wilkins Co .

Vol. 67 , No. 2 Print ed in U.S .A.

INTRANUCLEAR TONOFILAMENTS IN VERRUCA VULGARIS

KEN HASHIMOTO, M.D ., AND MASANOBU KUMAKIRI , M.D.

Veterans Administration Hospital and Division of Dermatology , Department of Medicine, The University of Tennessee Center for the Health Sciences, Memphis, Tennessee, U. S. A .

Electron microscopic examination of a verruca vulgaris has revealed the intranuclear inclusion of tonofibrils. Although many intracellular inclusions may be related directly to the virus , nonviral inclusions may also be present.

In the epidermis, intranuclear inclusion bodies have been described in keratinocytes in conditions including keratoacanthoma [1-8], leishmaniasis [9], and spongiform pustule of pustular psoriasis [10]. These inclusions are irregular in size and configuration and are now considered to be un­related to viruses or other organisms [8]. In Merkel cells, Fortman and Winkelmann [11] and later Straile et al [12] described more distinct nuclear inclusions such as filamentous [11] or rodlet [12] bodies. The origin of the latter inclusions was obscure although similar bodies have been seen in neurons of the central nervous system [13].

While it is possible that some of the nuclear inclusions are of nuclear origin , it is also possible that cytoplasmic organelles enter the nucleus dur­ing abnormal mitosis. Intranuclear Langerhans cell granules described in histiocytosis X [14,15] are an example. When epidermal keratinocytes undergo mitotic division, cytoplasmic organelles such as tonofibrils normally are shifted to the cell periphery. In abnormal mitosis , tonofibrils might be caught between the chromosomes. Such an example was found during examination of a ver­ruca vulgaris; namely, the intranuclear inclusion of tonofibrils. As far as we are aware, the only other report of such an inclusion is that of Gianotti et al [16 ].

MATERIALS AND METHODS

Several warts were removed by shave biopsy from a 7 -year-old male and processed routinely for electron microscopic examination. Briefly, fixation was done with 5% glutaraldehyde and 1 % osmic acid . The embedding medium was Araldite , and thin sections were cut at

o 400-600 A and stained with 15 % uranyl acetate in lOO % methanol and with lead citrate [17]. Stained sections were observed in an Hitachi HU-12 electron microscope operated at 125 kv .

. Manuscript received March 3, 1976: accepted for pub­lIcation April 20, 1976.

Dr. Hashimoto was supported by the Component Projects #3499 01 and #349902 and Medical Investigator­ship Award of the Veterans Administration.

Reprint requests to: Dr. K. Hashimoto, Veterans Administration Hospital , lO30 Jefferson Avenue, Mem­phis, Tennessee 38104.

RESULTS

Intranuclear filamentous inclusions were seen in a granular layer cell (Fig. 1). These inclusions were widely scattered through the nucleoplasm. The cell containing the inclusions was free from viral parti­cles but in other areas of the same specimen typical intranuclear inclusions of verruca virus were ob­served.

High magnification showed these filamentous inclusions to be bundled in a similar fashion to the cytoplasmic tonofilament~ of the same cell (Fig. 2) . Their diameters (50-60 A), electron density, and waving characteristics were identical to those of the cytoplasmic tonofilaments. There were no membranes enveloping these bundles; this ruled out a possibility of invagination of cytoplasmic tonofilaments into the nucleus. The widely scat-

FIG. 1. Intranuclear filamentous inclusions (.) III a granular cell . K: keratohyaline granule (x lO,OOO) .

285

286 HASHIMOTO AND KUMAKIRI Vol. 67, No.2

FIG. 2. A high magnification of filamentous intranuclear inclusions marked by (*) in Fig. 1. These bundles of filaments are identical to cytoplasmic tonofilament bundles (1') ( x 70,000) .

tered distribution of the inclusions further ruled out such possibility.

COMMENTS

In 1969, Gianotti, Caputo, and Califano [16] studied a case of epidermodysplasia verruciformis (Lewandowsky and Lutz). They divided lesions

into plane warts, common warts, and proliferative malignant lesions. They found intranuclear fibril­lar structures which were undergoing clear-cut neoplastic proliferation and discussed these inclu­sions in line with similar inclusions found in myeloma [18] and other virus diseases [19,20]. Obviously, they could have identified these inclu-

Aug. 1976

sions as tonofibrils if they had studied the struc­tures at a higher magnification as we did in this study. Intranuclear strands that were described by Dunn and Ogilvie in condylomata acuminata [19] appear to be unlike tonofibrils.

Since the initial identification of viral particles depends upon the ultrastructural examination of the suspected tissues, accurate classification of inclusion bodies is very important. Nonviral inclu­sions must be excluded and true viral inclusions must be established. In this manuscript we have identified one of many nonviral inclusions which may be found in verrucae.

REFERENCES

1. Zelickson AS : Virus-like particles demonstrated in keratoacanthomas by electron microscopy . Acta Derm Venereol (Stockh) 42:23-26, 1962

2. Zelickson AS , Lynch FW: Electron microscopy of virus-like particles in a keratoacanthoma. J Invest Dermatol 37:79-83, 1961

3. Forck G, Fromme HG, Jordan P: Zur Virusatiologie des Keratoakanthoms . Hautarzt 16: 153-155, 1965

4. Forck G, Fromme HG, Jordan P: Virusahnliche Teilchen beim Keratoakanthom. Dermatologische Wochenschrift 152:1029-1031, 1966

5. Bierwolf D, Thormann T: Zur Frage der Virusatiolo­gie des Keratoakanthoms . Dermatologische Wo­chenschrift 151:967-977, 1965

6. Nasemann T: Elektronenoptische Beobachtungen an einem Akanthom mit sicherer Virusatiologie in Analogie zu den Befunden am Keratoakanthom. Hautarzt 16: 156-158, 1965

7. Thivolet J, Leung TK, Moulin G, Sepetdjan M, Lieux JM: Keratoacanthome geant. Ann Dermatol Syphiligr (Paris) 93: 137-146, 1966

8. Sagebiel R: Non-specific inclusions in epidermal cells

INTRANUCLEAR TONOFILAMENTS IN VERRUCA VULGARIS 287

of keratoacanthoma. J Invest Dermatol 46:293-296, 1966

9. Forck B, Fromme GG, Herwig R: Ein Beitrag zur Kenntnis der Kernkorperchen in der pathologisch veranderten Epidermis. Arch Klin Exp Dermatol 235:418-436, 1969

10. Rupec M: Zur Ultrastruktur der spongiformen Pus­tel. Arch Klin Exp Dermatol 239:30-49, 1970

11. Fortman GJ, Winkelmann RK: A Merkel cell nuclear inclusion. J Invest Dermatol 61:334-338, 1973

12. Straile WE, Tipnis UR, Mann SJ, Clark WH Jr: Lattice and rod let nuclear inclusions in Merkel cells in rabbit epidermis . J Invest Dermatol 64: 178-183, 1975

13. Willey T J, Schultz RL: Intranuclear inclusions in neurons of the cat primary olfactory system. Brain Res 29:31-45, 1971

14. Wolff K , Sollereder B: Intranuclear and extracellular Langerhans cell granules. J Invest Dermatol 52:424-429, 1969

15. Gianotti F, Caputo R: Skin ultrastructure in Let­terer-Siwe d-isease treated with vinblastine. Br J Dermatol 84:335-354, 1971

16. Gianotti F, Caputo R, Califano A: Ultrastructural study of epidermodysplasia verruciformis Lewan­dowsky and Lutz: demonstrations of the virus and its correlation with clinical changes. Arch Klin Exp Dermatol 235:161-172, 1969

17. Reynolds ES : The use of lead citrate at high pH as an electron-opaque stain in electron microscopy . J Cell BioI 17:208-212, 1963

18. Bestetti-Bosisio M, Lanzavecchia G: Aspects uItra­structuraux des plasmocytes d 'un nodule mye­lomateux osseux. Nouv Rev Fr Hematol5 :221-240, 1965

19. Dunn AEG, Ogilvie MM: Intranuclear virus particles in human genital wart tissue: observations on the ultrastructure of the epidermal layer. J Ultrastruct Res 22:282-295 , 1968

20. Rowe WP, Capps WL: A new mouse virus causing necrosis of the thymus in newborn mice . J Exp Med 113:831, 1961