Malignant Melanoma of the Gallbladder

Path. Res. Pract. 163,281-287 (1978)

Rare and Unusual Cases

1St Department of Pathology and Laboratory of Electron Microscopy, Fukuoka University, Iizuka Hospital, Fukuoka, Japan

Malignant Melanoma of the Gallbladder Y. HATAE, M. KIKUCHI, M. SEGAWA, and K. YONEMITSU

Summary A rare case of primary malignant melanoma of the gallbladder was studied with the electron microscope. Two interesting patterns were observed: numerous melanophages were present in the tumor tissue and wrapped compound melanosomes were found in nonneoplastic mucosal epithelium. The infiltration of melanophages was considered to be a reaction to degenerated tumor cells. Concerning the mechanism of melanosome transport into the epithelial cells, a cooperative action between epithelial and melanoma cells seemed to be the most important factor.

Introduction Primary malignant melanoma of the gallbladder is a rare tumor. There seem to be no reports on ultrastructural studies of this tumor of the gallbladder in the literature. This report describes the electron microscopic features of a malignant melanoma which was interspersed with abundant histiocytes containing melanin pigment and being regarded as tumor cells light microscopically. Also the mechanism of incorporation of melanosomes into epithelial cells was studied.

Case History A 72-year-old man was admitted to the Iizuka Hospital because of right upper abdominal pain of two months duration. The gallbladder could not be visualized by cholangiography. On May 27, 1977, a cholecystectomy was performed under a tentative diagnosis of cholelithiasis. The gallbladder was enlarged to a man's fist size. No gallstones were found in the gallbladder. However, the cystic duct was obstructed by an irregular, ill-defined solid black tumor, measuring 2 X 2 em (Fig. 1). The postopera-

282 . Y. Hatae, M. Kikuchi, M. Segawa, and K. Yonemitsu

t

Fig.

I.

Transverse section of cystic duct. Tumor shows an expansive growth. HE; X 5.

Fig. 2. Tumor consists of a compact proliferation of pleomorphic cells with fine granules in the cytoplasm. Some epithelial cells also contain small amounts of granules. HE; X 320.

Malignant Melanoma of the Gallbladder . 283

Fig. 3. Neoplastic melanocy tes include numerous, round melanosomes, measuring 0. 5 to 1.0 I-lm in diameter and containing various amounts of electrondense amorphous materials. X 4,000.

Fig. 4.

Melanophages colltai n many compound melanosomes. X 5,400.

28 4 . Y. Hatae, M. Kikuchi, M. Segawa, and K. Yonemitsu

Fig. 5. Some compound melanosomes containing several dense materials are grouped near the nucleus in epithelial cells. )< 3,900.

tive course was smooth and he has no evidence of recurrence and no suggestion of this tumor elsewhere on Feb. 9, 1978. Histologically the tumor consists of a compact proliferation of round or polygonal cells, irregular in size and shape, with brownish-black, fine granules in the cytoplasm, ranging from sparce to numerous. Mitotic figures are not prominent. Some epithelial cells covering the tumor tissue and distant areas contain small amounts of brownish-black granules in the cytoplasm (Fig. 2). These granules stain black with the Masson-Fontana method. For electron microscopy, portions of formalin-fixed tissue from the tumor and pigmented epithelium were refixed in 3% glutaraldehyde, postfixed in 10f0 OS04 and embedded in epoxy resins. Ultrathin sections were stained with uranium acetate and lead citrate and examined with the JEM 100B electron microscope. The tumor tissue consists of 2 types of cells. The first type includes moderate to numerous melanosomes which are round in shape, measure 0.5 to 1.0 lAm in diameter and contain various amounts of electron-dense amorphous materials (Fig. 3). Fibrillary structures were observed in some melanosomes. These findings are consistent with those found in melanoma cells. The second type cells contain compound melanosomes with 10 to 20 melanosomes enclosed by a unit membrane (Fig. 4). An eccentric, angular nucleus, an irregular cells border and numerous compound melanosomes suggest a histiocytic origin of the cells. In the epithelial cells containing melanin pigment, melanosomes were

Malignant Melanoma of the Gallbladder . 285

found in groups, wrapped by a thin unit membrane and situated mainly near the nucleus (Fig. 5). No pinocytotic vesicles or membrane-free melanosomes were seen.

Discussion There are only few reports on malignant melanoma of the gallbladder in the literature (Wieting and Hamdi, 1907; Rosenthal, 1931; Walsh, 1956; Jones, 1961; Raffensperger et al., 1963; Peison and Rabin, 1976; SierraCallejas and Warecka, 1976). The problem is whether or not a melanoma found in the gallbladder has taken its origin from the gallbladder. Masson (1948) stated that a primitive melanoma could occur at any site where elements from the neural crest were distributed. Breathnach (1969) reported that melanocytes appear in the ovary, adrenal medulla and gallbladder. In our case, the histologically malignant appearing tumor was present only in the gallbladder and no tumor was found in any other site of the body. Since malignant melanoma of the gallbladder is a rare tumor, sufficient investigations of its histologic pattern have not been made, especially not with the electron microscope. In this report, two interesting microscopic patterns are described: one is the presence of numerous melanophages in the tumor tissue and the other the pattern of melanosome distribution in the epithelial cells. Liban (1969) pointed out that in malignant melanoma many melanophages may often be intermingled with the tumor cells. However, there have been no reports on coexisting melanophages in malignant melanoma of the gallbladder except in Rosenthal's (1931) case in which the presence of histiocytes around the tumor was described. In our case, many cells containing abundant brownish-black cytoplasm when stained with HE and appearing yellow after toluidine blue staining correspond to melanophages with compoud melanosomes under the electron microscope. These melanophages are distributed throughout the tumor tissue. These findings suggest the possibility that melanophages which are intermingled with the tumor cells may be regarded as tumor cells by light microscopy. A number of degenerating melanocytes and free melanosomes are also scattered throughout the tumor tissue. The infiltration of melanophages is therefore considered to be a reaction to degenerated tumor cells. Regarding melanosomes in the epithelial cells, Rosenthal (19 3I) described gland-like structures lined by flat cuboidal epithelium with pigment 19

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286 . Y. Hatae, M. Kikuchi, M. Segawa, and K. Yonemitsu

granules in the cytoplasm in melanoma of the gallbladder. He misunderstood these findings as being suggestive of the epithelial origin of malignant melanoma. No reports are available in the literature about the presence of melanosomes in the surrounding epithelial cells in malignant melanoma. It is of particular interest how melanosomes get into the epithelial cells. In our case, melanosomes are found in the epithelial cells outside the main tumor. Hayward (I 962) has already reported on the pinocytotic activity of epithelial cells of the gallbladder, but not pinocytotic vesicles were observed in this case. It is generally accepted that melanosome transport from dendritic melanocytes may be caused by the cooperative action of epithelial cells and melanocytes (Cruickshank; I964). It is questionable whether epithelial cells other than epidermal cells, especially columnar epithelial cells of the gallbladder, may play an active role in the transport of melanosomes. We did not observe epithelial cells engulfing a part of melanoma cells, but melanosome transport from melanoma cells must be due to the same cooperative action as is seen between melanocytes and epidermal cells because of the distribution and size of melanosomes and absence of pinocytotic vesicles in epithelial cells.

References I. Breathnach, A. S.: Normal and abnormal melanin pigmentation of the skin. In: Pigments in pathology, Wolman, M., vol. I, pp. 355. Academic Press, New York (1969) 2. Cruickshank, C. N. D., and Harcourt, S. A.: Pigment donation in vitro. J. Invest. Derm. 42,183-184 (1964) 3. Hayward, A. F.: Electron microscopic observations on absorption in the epithelium of the guinea pig gallbladder. Z. Zellforsch. 56, 197-202 (1962) 4· Jones, C. H.: Malignant melanoma of gallbladder. J. Path. Bact. 81, 423-430 (1961) 5. Liban, E.: Pigmented nevi and malignant melanomas. In: Pigments in pathology, Wolman, M., vol. I, pp. 44I. Academic Press, New York (1969) 6. Masson, P.: Pigment cells in man. In: The biology of melanomas, pp. 15-51. Spec. pub!. N.Y. Acad. Sci., New York (1948) 7. Peison, B., and Rabin, L.: Malignant melanoma of the gallbladder. Report of three cases and review of the literature. Cancer 37, 2448-2454 (1976) 8. Raffensperger, E. c., Brason, F. W., and Triano, G.: Primary melanoma of the gallbladder. Amer.]. Dig. Dis. 8, 356-363 (1963) 9· Rosenthal, S. R.: Primary melanocarcinoma of the gallbladder. Amer. ]. Cancer 15, 2288-2300 (J 93') 10. Sierra, Callejas, ]. L, and Warecka, K.: Primary malignant melanoma of the gallbladder. Virchows Arch. A Path. Anat. Histol. 370, 233-238 (1976) 1 I. Walsh jr., ]. S.: Primary melanoma of the gallbladder with cervical metastasis and fourteen and onehalf year survival. Cancer 9,518-522 (1956)

Malignant Melanoma of the Gallbladder . 28 7 12. Wieting and Hamdi: Dber die physiologische und pathologische Melaninpigmentierung und den epithelialen Ursprung der Melanoblastome. Ein primares Melanoblastom der Gallenblase. Beitr. Path. 42,23-84 (1907)

Received March 19, 1978 . Accepted in revised form June 27, 1978

Key words: Gallbladder - Malignant melanoma - Melanoma ultrastructure - Electron microscopy Y. Hatae, 1St Dept. of Pathology, Fukuoka University, Nanakuma, Nishiku, Fukuoka, Japan