Sebaceoma and related neoplasms with sebaceous differentiation: a clinicopathologic study of 30 cases

The classification of benign sebaceous neoplasms has been challenged both by the assertion that sebaceous adenomas are really carcinomas and by difficulties in drawing the boundaries between sebaceomas and other lesions. We performed a clinicopathologic study of 30 cases of basaloid neoplasms with sebaceous differentiation, excluding cases of definite sebaceous carcinoma with severe nuclear atypia invading deep within the subcutaneous tissue and those of ocular sebaceous carcinoma. We tried to classify sebaceous neoplasms in six categories with defined histopathologic criteria. All the neoplasms were characterized by aggregations of basaloid cells admixed with sebocytes and sebaceous duct-like structures located in the dermis with or without connection to the epidermis. The categories were 1) sebaceoma (14 cases); 2) trichoblastoma with sebaceous differentiation (3 cases); 3) apocrine poroma with sebaceous differentiation (2 cases); 4) low-grade sebaceous carcinoma (6 cases); 5) sebaceous carcinoma (4 cases); and 6) basal cell carcinoma with sebaceous differentiation (1 case). The sebaceoma was further subclassified as classic type (12 cases) or verruca/seborrheic keratosis type (2 cases). Although most sebaceomas can be distinguished from other lesions, there are problematic cases. We discuss the histopathologic diagnostic problems associated with sebaceoma and also argue in favor of the concept of sebaceous adenoma.     

Cornification (keratinization) in Basal cell carcinoma: a histopathological and immunohistochemical study of 16 cases

The concept of keratotic BCC is obscure and not well-defined. To elucidate the histopathological and immunohistochemical properties of cornification in BCC and to clarify the concept of keratotic BCC, by careful examination of 600 BCC specimens, we selected 16 cases of BCC that showed cornification. We investigated the precise histopathological features of these 16 cases, and studied the immunohistochemical expression patterns of anticytokeratin (CK) antibodies (CKs 1, 10, 13, 14, 17) and other antibodies in these cornifying (keratotic) BCCs. We compared these data to those from normal adult hair follicles and three types of cornifying cysts (epidermal cyst, tricholemmal cyst and steatocystoma). Six types of cornification were observed in these BCCs; 1) infundibular type (4 cases) with thin laminated corneocytes expressing CKs 1 and 10, 2) tricholemmal (isthmus) type (9 cases) showing compact, homogenous cornified contents with CK 17 expression on the surrounding cells, 3) inner root sheath type (1 case) characterized by compact, blue-gray corneocytes lined by CK 13 positive-squamous cells with red trichohyalin granules, 4) sebaceous duct type (1 case) characterized by crenulated cornified cells expressing CK 17, 5) apocrine acrosyringium type (2 cases) characterized by small duct-like structures lined by eosinophilic cuticle expressing CEA, in association with keratohyaline granules, and 6) cornifying microcyst type (10 cases) characterized by micro and small cystic structures containing the debris of cornified cells, which was associated with the infundibular or tricholemmal type and could be classified as having the primitive features of the tricholemmal type of cornification. The tricholemmal type could be subdivided into two groups: one with keratohyaline granules and the other without keratohyaline granules, and the cornified contents in approximately 30% of the cornified areas in this type were positive for CK 17. The matrical type of cornification (seventh type) was not seen in our study. The examples described as "keratotic BCC" thus far were similar to BCCs with cornification of the tricholemmal (isthmus) or infundibular type. The cornification in BCCs could be classified into seven types. Excluding the cornifying microcyst type, the tricholemmal type is the most common type of cornification. This type will be abnormal and incomplete in attempts to cornify in the form of an isthmus, occasionally with concomitant exhibition of lower infundibular differentiation. The keratotic BCC is considered to be BCC with cornification of the tricholemmal (isthmus) or infundibular type.     

Rippled-pattern basal cell carcinoma

Basal cell carcinoma (BCC) is the most common malignant cutaneous neoplasm, however, there have been few studies on BCC with a "rippled pattern" so far. We reviewed the 650 BCC specimens from the archives of our institution, and only one example of BCC with a rippled pattern was found. We herein report the histopathological characteristics of this case. Within the lesion, which showed the typical histopathological features of nodular BCC, there was a noticeable area composed of 10-15 basaloid aggregations, which showed the rippled pattern. The rippled pattern was characterized by alternating bands of epithelial cords of spindle-shaped basaloid cells and mucinous spaces. Characteristically, around the rippled-pattern area, neoplastic aggregations with a mucinous reticulated or cystic pattern (pseudo-tubular structures), and many cord-like structures were seen. A review of the published work and the present case suggested that the histopathological characteristics of rippled-pattern BCC are: (i) a nodular type of BCC; (ii) considerably rare; (iii) have frequent intervention by mucinous spaces between the epithelial cords; and (iv) no apparent divergent differentiation with folliculosebaceous-apocrine lineage. The last three characteristics contrasted with those of the rippled-pattern sebaceoma/trichoblastoma. However, neoplastic germinative cells in rippled-pattern BCC may naturally form cord-like structures in a manner similar to rippled-pattern sebaceoma/trichoblastoma.     

A single lesion showing features of pigmented eccrine poroma and poroid hidradenoma

Poroid hidradenoma (PH) is a variant of poroma. This entity was defined by Abenoza and Ackerman in 1990. This neoplasm shows architectural characteristics of hidradenoma (tumor cells confined entirely within the dermis in both solid and cystic components) and cytologic characteristics of poroid neoplasm (poroid and cuticular cells, the latter showing ductal differentiation). We herein document a case of single poroid lesion with the features of both eccrine poroma and PH. The patient was a 55-year-old woman with a pigmented nodular lesion on her upper back for 7 years. The histopathologic features of the lesion were consistent with those of eccrine poroma and PH. Unlike most eccrine poromas, this case was pigmented, clinically and microscopically.     

Nestin expression in stromal cells of trichoblastoma and basal cell carcinoma

Background Both trichoblastoma and basal cell carcinoma (BCC) are considered to be a benign and malignant neoplasm of follicular germinative cells respectively. A recent investigation revealed that the mesenchymal cells in the perifollicular sheath and evolving follicular papilla of embryonic hair germs and those cells in hair follicles in early anagen express nestin. Objective The aim of the present study was to investigate whether trichoblastoma and BCC recapitulate the epithelial–mesenchymal interactions in embryonic hair germs or early anagen hair follicles by expressing nestin in stromal cells. Methods Immunohistochemical staining was performed with antibody against nestin for 15 trichoblastomas including large/small nodular, retiform and trichoepithelioma types, while adding the superficial type associated with nevus sebaceous and for 20 BCCs including superficial, nodular, nodulo‐infiltrative, and infiltrative/micronodular types. Results In all 15 trichoblastomas, the stromal cells expressed nestin with variable positive reactions, except for superficial trichoblastomas within nevus sebaceous lesions, in which stromal cells were constantly positive for nestin. In all 20 BCCs, the stromal cells were basically negative for nestin. Conclusions The development of trichoblastomas incompletely recapitulates the epithelial–mesenchymal interactions in embryonic hair germs or early anagen hair follicles, whereas BCCs fundamentally have lost this ability. Among the various types of trichoblastomas, the superficial type associated with nevus sebaceous was found to have the most similar character to either embryonic hair germs or early anagen hair follicles.     

Sebaceous carcinoma with apocrine differentiation

A 54-year-old male had a dome-shaped and skin-colored nodule on his nose. Histopathologically, we diagnosed this neoplasm as a low-grade sebaceous carcinoma rather than a sebaceoma based on the scanning magnification and cytology. This low-grade sebaceous carcinoma was associated with glandular structures. We regarded the glandular structures as those of apocrine glandular differentiation based on 1) the histopathologic features of the glandular structures formed by columnar luminal cells with evidence of decapitation secretion; 2) the expression of cytokeratin (CK) 19, CK8, CK8/18, and CK7 in the luminal cells; 3) the positive reaction of carcinoembryonic antigen and epithelial membrane antigen on the luminal surface and in the cytoplasm of the luminal cells; and 4) the common embryologic origin of the folliculosebaceous-apocrine unit. We found CK15 expression in undifferentiated cells within the mantles of normal hair follicles, suggesting that sebaceous stem cells might exist in mantles as follicular stem cells exist in bulge areas. Pluripotent stem cells in the folliculosebaceous-apocrine unit can give rise to follicular stem cells, sebaceous stem cells, and apocrine stem cells. Our patient's neoplasm showed apocrine glandular differentiation and partial immunohistochemical positivity for CK15 in the neoplastic aggregations. We believe this neoplasm originated from pluripotent stem cells destined to become sebaceous stem cells or from sebaceous stem cells, which also have the ability to differentiate within apocrine glands.     

Proliferation patterns reflect architectural dedifferentiation: a study of nodular basal cell carcinoma

The distribution of proliferating cells in basal cell carcinoma (BCC) may be related to lesion type and architecture. Single proliferation indexes may not be representative. We aimed to establish the distribution of cell proliferation in BCC as related to architecture. We studied an unselected, consecutive series of 45 resection specimens of nodular BCC from patients in the age range of 25-95 years using MIB-1 staining and systematically reviewed the cases. These lesions included nodular (n=32) and non-nodular (n=9) BCC. Within the nodular BCC, two patterns were recognised, not related to age or gender. In small nodular patterns with well developed peripheral palisading and central parallel streaming of small, elongated nuclei, proliferation is limited to the basal palisading cells in a clustered distribution. In large nodular patterns, proliferation is absent at the basal membrane (BM) and distributed in single random cells throughout the lesion. Both patterns preclude accurate quantitation. Many lesions contained both patterns in a side-by-side, unmixed manner. These pattern differences suggest a loss of differentiation in nodular BCC. Perhaps a single mutation results in the loss of BM associated cell architecture and proliferation control related to tumor-stroma interactions. As a result, the lesion reverts to a low frequency, non-regulated proliferation, diffusely distributed throughout the lesion. The two patterns may exist side-by-side in a single lesion, further supporting the concept of polyclonality. This hypothesis explains perilesional clefting and previously reported variations in intra-lesional laminin synthesis. Based on our findings, representation of tumor cell proliferation activity by a single value is not justified. Nodular BCC exists in one of two dedifferentiation-mutation-determined patterns of cell proliferation; many lesions clearly demonstrate bi-clonality.     

Basal cell carcinomas in association with basaloid follicular hamartoma

We describe a unique case of various types of basal cell carcinoma (BCC) associated with basaloid follicular hamartoma (BFH) in a 56-year-old female patient. The lesion consisted of a dark brown and elastic soft nodule and papules within the area of a birthmark on the neck. The lesion was surgically excised. Histological examination of the nodular region revealed aggregations of neoplastic basaloid cells. We diagnosed the nodule as BCC with a racemiform or reticular pattern. In addition, a specimen taken from brownish black papules within the birthmark was found to be composed of anastomosing cords of basaloid cells accompanied by infundibular cystic structures. These features were consistent with an infundibulocystic BCC. In contrast, specimens from a hamartomatous plaque showed distinctive branching strands of basaloid cells that are suggestive of BFH. Therefore, our findings indicate that several types of BCC may develop within a BFH.     

Dendritic cells in pigmented basal cell carcinoma: a relevant finding by reflectance-mode confocal microscopy

BACKGROUND: Reflectance-mode confocal microscopy (RCM) is a new approach for the in vivo diagnosis of skin tumors. A few studies of RCM on basal cell carcinoma (BCC) have provided specific diagnostic criteria, but large studies on pigmented basal cell carcinoma are lacking. Proliferation of large dendritic-shaped cells within a melanocytic tumor has been associated with the diagnosis of melanoma by RCM. Benign melanocytes and Langerhans cells may populate BCC according to previous histological studies. We studied 3 consecutive pigmented BCC by means of RCM and performed a histological and immunohistochemical correlation focusing on the presence of dendritic structures. OBSERVATIONS: Reflectance-mode confocal microscopy revealed highly refractive dendritic structures within tumor nests that correlated with the presence of melanocytes within the tumor by immunochemical analysis. In 1 case, dendritic structures on the overlying epidermis corresponding to Langerhans cells were also noted. Leaf-like areas observed on dermoscopy correlated with low-refractive cordlike structures and nodules by RCM and corresponded to nests of basaloid cells, whereas blue-gray globules presented as bright oval structures with ill-defined borders corresponding to melanophages. CONCLUSIONS: Reflectance-mode confocal microscopy allows the study of pigmented BCC and the identification of specific criteria described previously. In these tumors, dendritic melanocytes can be easily identified with this technique.     

Muir-Torre syndrome: a case of this uncommon entity

A 69-year-old Hispanic woman presented for the evaluation of nodules on the head and back. In the past, she had been treated for basal cell carcinoma (BCC) of the face; the referring physician was concerned that the new lesions might also be BCC. The patient had an extensive past medical history. In addition to BCC, she had been treated for breast cancer, colon cancer, and cervical cancer prior to emigrating to the USA. Her colonic malignancy had been localized proximal to the splenic flexure. She also had a history of colonic polyps and distal colonic villous adenoma. She denied ever being treated with radiation. Further details of her medical history and cancer staging were not available. Her family history was significant for a sister with colon cancer and transitional cell carcinoma of the urinary bladder. In addition, she had a great aunt with oral cancer and a great uncle with lung cancer. Neither the patient or her relatives had any history of tobacco use. On physical examination, in addition to scars from a radical mastectomy and midline abdominal laparotomy, four skin lesions were noted: two on the scalp, one on the tragus, and one on the mid-back. The first lesion on the vertex of the scalp was a yellow-brown waxy papule measuring 0.6 x 0.5 cm. This lesion was similar to that on the mid-back, except in size. The lesion on the back measured 1.2 x 1.0 cm. The second lesion on the frontal scalp measured 0.8 x 0.6 cm and was red-brown with a pearly appearance and some central hyperkeratosis. The tragus lesion was similar in appearance to that on the frontal scalp. Shave biopsies of all lesions were obtained. The lesions on the scalp and mid-back revealed lobules of sebaceous cells in the dermis with a minority of surrounding basaloid cells, consistent with a diagnosis of sebaceous adenoma (Fig. 1). Although the lesion on the frontal scalp also showed sebaceous differentiation, there were a greater number of basaloid cells, some with hyperchromatic nuclei and mitotic figures; this was consistent with a diagnosis of sebaceous epithelioma (Fig. 2). The final lesion (tragus) was histologically consistent with a keratotic BCC. No further treatment was required for these benign sebaceous tumors, but their presence defined our patient's condition as Muir-Torre syndrome. Mohs' micrographic surgery was performed on the tragus BCC and the margins were tumor free in one stage. The patient returned 1 year later with a lesion anterior to the left axilla which was biopsied to rule out BCC (Fig. 3). Histologically, this lesion was also consistent with sebaceous epithelioma.     

Basaloid squamous cell carcinoma with 'monster' cells: a mimic of pleomorphic basal cell carcinoma

Pleomorphic giant or 'monster' cells represent a well-recognized yet uncommon finding associated with basal cell carcinoma (BCC), usually of nodular type. We present a case of basaloid squamous cell carcinoma (basaloid SCC) with 'monster' cells that closely mimicked those described in pleomorphic nodular BCC. Clinically, the lesion presented as a fleshy, hyperkeratotic nodule in an 82-year-old woman. Histopathology revealed a basaloid lesion with lobulated borders and focal retraction artifact but a lack of prominent palisading or stromal mucin. There were areas of necrosis and small foci of keratinization. Striking bizarre monstrous pleomorphic nuclei were widely scattered throughout the lesion. Ber-EP4 immunohistochemistry proved to be negative and epithelial membrane antigen (EMA) expression was moderate to strong in 70% of the basaloid epithelium. Monster cells have not previously been highlighted in cutaneous SCC or in its uncommon cutaneous basaloid variant. The prognostic significance of monster cells is unknown but, given the relative paucity of keratinization in basaloid SCC, these lesions should probably be regarded as poorly differentiated. We have not previously encountered an SCC that so closely resembles nodular BCC with pleomorphic monster cells and believe that this is the first such report in the literature.     

An unusual apocrine carcinoma on the forehead

We herein report an unusual case of apocrine carcinoma on the forehead. The lesion was formed by the anastomosis of numerous tubular structures with widespread decapitation secretion, thus demonstrating apocrine differentiation. However, we observed some unusual histopathologic features that differed from those found in typical examples of apocrine ductal carcinoma, namely: 1) a relatively well-circumscribed lesion in the dermis, and 2) nodular or solid aggregations composed of basaloid cells. We believe the present case is an apocrine ductal carcinoma, although it has a nodular appearance and basaloid cells. Otherwise, it could be a hitherto undescribed variant of apocrine carcinoma. This apocrine carcinoma on the forehead may have originated from either pluripotential cells or from apocrine glands at an unusual site.     

Congenital melanotic macules and Sebaceous Choristoma arising on the tongue of a newborn: epidermal choristoma?

Oral hyperpigmentation is a common event in older individuals, however, is exceptional in neonates (congenital melanotic macules). Conversely, 70-80% of people have sebaceous glands in the oral mucosa, with the tongue representing an ectopic location and termed sebaceous choristoma by some authors. We report a case that fulfills both conditions in a tongue lesion. A 1-month-old boy presented with a pigmented macula on his tongue noted at birth. An excisional biopsy was performed showing a lesion lined by an epidermal-like epithelium with basal pigmentation, under which, sebaceous glands, abortive hair follicles and ductal structures mimicking apocrine glands were found. Seven cases of congenital melanotic macules of the tongue have been reported, however, none of them showed sebaceous glands under the lesion. Furthermore, there has not been a reported case of sebaceous choristoma of the tongue present at birth. We present a case that shares clinical and histological features of both conditions and propose the name 'epidermal choristoma'.     

Pigmented Trichoblastoma Arising from the Nevus Sebaceous: A Rare Case in Korea

Trichoblastoma is occasionally observed in association with a pre-existing nevus sebaceous in the Korean literature. However, there has been no report on the pigmented type. Herein, we report the first Korean case of a pigmented trichoblastoma arising from the nevus sebaceous on the forehead. A 28-year-old male presented with a dark nodular lesion within a yellowish plaque on the forehead. The surrounding yellowish plaque on the forehead had existed since birth. The central, dark-pigmented nodule began to appear three years ago and enlarged gradually. Histopathologic findings of central pigmented lesion showed heavy melanin deposits within and around the tumor nests. Complete excision was made as treatment.     

Apocrine poroma: a distinctive case in a patient with nevoid basal cell carcinoma syndrome

Traditionally, poromas have been classified as eccrine neoplasms, but several recent reports of poroid tumors with sebaceous, follicular, and apocrine differentiation have challenged this idea. In support of alternative differentiation, a case of an "apocrine" poroma is reported in a 19-year-old man with the nevoid basal cell carcinoma syndrome. A papule on the right cheek, thought clinically to be a basal cell carcinoma, was excised. Anastomosing lobules of small uniform basaloid (poroid) cells formed small ductular structures lined by eosinophilic cuticles and extended into the superficial reticular dermis. The neoplasm originated from follicular infundibula and was surrounded by a myxoid stroma. Focally, primitive hair bulb and papillae differentiation was present, and some of the ducts were lined by cells suggesting decapitation secretion. The histologic pattern and the common embryologic origin of the folliculosebaceous-apocrine unit support apocrine differentiation of this tumor. The association with the nevoid basal carcinoma syndrome appears to be unique. This case, in addition, demonstrates overlapping features with the infundibulocystic type of basal cell carcinoma commonly seen in the basal cell nevus syndrome.     

A case of sebaceous carcinoma diagnosed in an adolescent male

Sebaceous carcinoma is an uncommon and potentially aggressive malignancy that exhibits sebaceous differentiation. Approximately 75% of cases arise in the periocular region. Sebaceous carcinoma is rare in the pediatric population and its presentation in this age group is not well documented in the dermatopathology literature. We report the case of a 15-year-old male with sebaceous carcinoma who was first seen with a nodular lesion involving the skin of the left orbit/temporal area. A shave biopsy was performed which showed an infiltrative proliferation of basaloid cells that focally exhibited sebaceous differentiation, including the formation of incipient sebocytes. Immunohistochemically, the tumor cells expressed epithelial membrane antigen (EMA) and CK5/6, while a lack of Ber-EP4 was observed. Based upon these attributes, the diagnosis of sebaceous carcinoma was rendered. Subsequent immunohistochemical analysis for a possible DNA mismatch repair enzyme defect revealed that all four mismatch repair gene products showed retained expression, thereby providing no support for the presence of underlying Muir-Torre syndrome. Sebaceous carcinomas are exceptional in the pediatric age group and are rarely documented in the dermatopathology literature. Knowledge that this adult carcinoma can occur mostly in the pediatric age group may aid in the recognition of this uncommon malignancy.     

Primary cutaneous biphasic sarcomatoid basal cell carcinoma with myoepithelial carcinoma differentiation: A new variant

Isolated cases of basal cell carcinoma (BCC) with partial myoepithelial component have been described. However, myoepithelial differentiation has not been described in sarcomatoid basal cell carcinomas, which usually show features resembling osteosarcoma, chondrosarcoma, or leiomyosarcoma. We report a case of an 87‐year‐old man with a forehead lesion that histologically showed a minor component of conventional nodular BCC in transition with a major biphasic sarcomatoid growth composed of invasive spindle‐cell and epithelial‐like components, the latter with a reticular pattern and scattered ductal structures. Both components showed cytological atypia and high mitotic rate (26/10HPF), with atypical mitotic figures. BER‐EP4 immunostaining was exclusively found in the nodular BCC component whereas the sarcomatoid component revealed immunostaining for α‐smooth muscle actin (SMA), muscle‐specific actin (MSA), calponin, and p63 in both epithelial‐like and spindle‐cell populations. Focal immunoreactivity was observed in the epithelial component for S100 and glial fibrillary acidic protein (GFAP). Furthermore, EWSR1‐PBX1 gene fusion was also detected. This is to our knowledge, the first fully documented case of biphasic sarcomatoid BCC with myoepithelial carcinoma differentiation.     

Cutaneous Mixed Tumor Containing Ossification,Hair Matrix,and Sebaceous Ductal Differentiation

A 58-year-old Japanese male presented with a cutaneous mixed tumor containing ossification and hair matrix differentiation on the left side of the chin. Histologically, the tumor consisted almost exclusively of apocrine-type epithelial ductal structures and chondroid stroma. Strands and aggregation of basaloid cells which contained keratinous cystic structures with a column of shadow cells arising from basophilic basaloid cells, sebaceous duct-like structures, and ossification in the stroma were also evident. These findings suggest that cutaneous mixed tumors with ossification and hair matrix differentiation are related to both the whole hair follicle and the sweat aparatus.     

Basal cell carcinoma with matrical differentiation in a transplant patient: a case report and review of the literature

BACKGROUND: Shadow cells, characterized by basaloid squamous cells with a distinct well-defined border and a central unstained area as a shadow of lost nuclei, are characteristic of pilomatricoma, a distinct neoplasm of hair matrix differentiation. The presence of shadow cells within tumor islands composed of follicular germinative cells of an otherwise classic basal cell carcinoma (BCC) has been considered as a distinct diagnostic category of BCC with matrical differentiation. We present a case of BCC with matrical differentiation in a transplant patient. To our knowledge, only 10 cases [Aloi et al. Am J Dermatopathol 1988; 10: 509; Ambrojo et al. Am J Dermatopathol 1992; 14: 293; Sagol et al. East J Med 1999; 4: 37; Kwittken J. Cutis 2002; 69: 57; Kim et al. Yonsei Med J 2003; 44: 523] of BCC showing matrical differentiation have been reported. None have been reported arising on the background of immunosuppression. METHODS: A 58-year-old male cardiac transplant patient with a nodule on the dorsum of left hand was studied. It arose and enlarged rapidly within a few months, causing irritation and bleeding. The nodule was surgically excised and submitted for histopathologic evaluation. The sections were prepared by hematoxylin and eosin (H&E) method. RESULTS: The H&E-stained sections of the hand lesion revealed multiple nodular masses of basaloid follicular germinative cells. In some areas, there was peripheral palisading and stromal retraction artifact typical of classic BCC. In these areas, the tumor nodules were connected to the epidermis, whereas in others, it extended deep into the reticular dermis to the subcutaneous fat junction. Elsewhere, the majority of the tumor contained a population of shadow cells, similar to those in pilomatricoma, with basaloid-appearing matrical cells in the periphery. Trichohyaline granules were identified in the cytoplasm of many of the peripheral basaloid cells. These granules are one of the characteristic features of follicular matrix differentiation. Mitoses were rare. Areas of cystic degeneration were present throughout the tumor. There was no evidence of an infiltrating growth pattern, lymphovascular invasion, or sarcomatoid growth pattern. CONCLUSION: BCC with matrical differentiation is a distinct pathologic entity and a rare subtype of BCC featuring shadow and matrical cells, typically seen in pilomatricoma, a benign hair matrix neoplasm. This tumor has not yet been reported in an immunosuppressed transplant patient.