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Michal Michal

Publications and source records attributed to Michal Michal.

At least 19 recordsLinked to original sources
PubMed2025

Deciphering Pseudoendocrine Sarcoma: A Clinicopathological, Molecular, and Epigenetic Study Suggesting Biological Links With Solid Pseudopapillary Neoplasm of the Pancreas.

Pseudoendocrine sarcoma (PS) is a recently described neoplasm of uncertain differentiation, characterized by recurrent CTNNB1 mutations, frequent paravertebral location, and a neuroendocrine-like histomorphology. In this study, we report the clinicopathologic, immunohistochemical, transcriptomic, and epigenetic findings of 12 PS cases. The tumors affected 7 men and 5 women with a median age of 66 years and were located in the paraspinal/paravertebral region (n = 11) and the thigh (n = 1). Median tumor size was 82 mm (range, 32-170 mm). Histologically, the tumors comprised sheets and nests of epithelioid-to-ovoid cells with uniform nuclei and speckled chromatin, frequently associated with extracellular hyaline globules and fibrovascular cords/septa. Uncommon findings included microcalcifications, myxoid stroma, pseudopapillary, pseudoglandular, microcystic or corded architecture, and lumen and rosette-like structures. Necrosis was absent, and mitotic activity was low. On immunohistochemistry, the tumors showed aberrant nuclear staining for beta-catenin (8/8) and expression of CD56 (7/7), S100 (8/8), desmin (2/6), and androgen receptor (1/4). Pankeratin (AE1/AE3), progesterone receptor, synaptophysin, chromogranin, and INSM1 were negative. All tested cases harbored CTNNB1 mutations. Using a customized cohort, methylation profiling revealed that PS formed a common cluster with solid pseudopapillary neoplasm of the pancreas (SPNP), distinct from all methylation classes from the Heidelberg sarcoma classifier and a subset of paragangliomas. Transcriptomic analysis showed that PS formed an independent cluster from a control group of tumors (including SPNP). Differential gene expression analysis showed enrichment in genes of the Wnt signaling pathway (HALLMARK gene sets) and biological processes related to sensory perception, among others (gene ontology - biological process [GO-BP]). Additionally, upregulated genes were related to various fetal cell types from the cell type signature data set (MSigDB), particularly of neuronal and epithelial lineage. Immunohistochemical assessment of potential markers identified through gene expression analysis revealed focal-to-diffuse expression of GLUT1 (6/6) and focal/multifocal expression of Brachyury (4/9) and HuD (3/7). Follow-up information, available for 10 cases (median duration of 18 months; range, 7-69 months), showed local recurrences and metastatic spread in 2 patients each. Evidence of response to radiotherapy was documented in one tumor. Altogether, this study expands knowledge on PS and suggests biological links with SPNP, including a potential shared cell of origin.

Humans↗
PubMed2007

Angiomatous spindle cell lipoma: Report of three cases with immunohistochemical and ultrastructural study and reappraisal of former 'pseudoangiomatous' variant.

Pseudoangiomatous spindle cell lipoma (PASCL) is a rare variant of spindle cell lipoma that is composed of spindle fibroblast-like cells and mature adipose cells, and that is further characterized by intratumoral branching spaces regarded originally to be non-vascular (hence the adjective 'pseudoangiomatous'). Reported herein are three cases of this tumor, with literature review of all six cases described previously. PASCL appears to have clinical features (age, sex, location, prognosis) similar to those of conventional spindle cell lipoma (SCL). Immunohistochemically, the spindle cells in all of the present cases were positive for CD34, as in conventional SCL. All lesions had at least mild positivity for sex steroid hormone receptors. The cells lining intratumoral dilated and branching spaces typical of this variant were strongly positive for lymphatic endothelial marker D2-40 in all cases, and for vascular markers CD31 and F-VIII in one case. Ultrastructural study confirmed the endothelial nature of these cells. The results indicate that pseudoangiomatous SCL is truly angiomatous and should be termed as such. It could represent a sex steroid hormone-dependent lesion.

Aged↗
PubMed2006

Cotyledonoid dissecting leiomyoma of the uterus with intravascular growth: report of two cases.

We present two cases of cotyledonoid dissecting leiomyoma of the uterus with intravascular involvement, which occurred in women aged 73 and 48 years. Grossly and microscopically, both neoplasms had an extrauterine cotyledonoid part and intrauterine dissecting fascicles of disorganized, swirled neoplastic smooth muscle with hydropic degeneration and foci of an intravascular growth (the latter was identified histologically). To our knowledge, the intravascular component of such a neoplasm is a very rare feature that has previously been described only in three cases in the literature.

Aged↗
PubMed2006

Mixed germ cell sex cord-stromal tumors of the testis and ovary. Morphological, immunohistochemical, and molecular genetic study of seven cases.

We present the morphological, immunohistochemical, and molecular genetic features of three cases of testicular and four cases of ovarian mixed germ cell sex cord-stromal tumors (MGSCT). The germ cells in the testicular MGSCTs morphologically differed from those in classical seminomas by lacking the typical "square off" quality of the nuclei. In contrast to the nuclei in classical seminomas, their size in testicular MGSCTs was smaller and nucleoli were inconspicuous and the cytoplasm was Periodic Acid-Schiff (PAS) negative. Quite on the contrary, the variability in the size of the nuclei of the germ cells in the testicular MGSCTs was more similar to that seen in the germ cells of spermatocytic seminomas. Immunohistochemically, the germ cells of MGSCTs in one case reacted positively with antibody to AE1-AE3 by paranuclear dot-like or rodlike positivity. All three testicular MGSCTs had a negative reaction with the rest of antibodies, including placental alkaline phosphatase (PLAP), OCT4, and c-kit protein. Ovarian MGSCT in our series differed from the testicular lesions in both the germ cell component and the sex cord component. The germ cells in all four ovarian cases had cytomorphological and immunohistochemical features identical to those in classical seminomas/dysgerminomas. They possessed the typical "square off" quality of the nuclei, which were much more blastic, with more mitoses compared with the testicular tumors in our series, and they were PLAP (4/4), OCT4 (4/4) and c-kit protein (3/4) positive immunohistochemically. The cytoplasm of the germ cells in ovarian neoplasms contained PAS positive glycogen. Germ cells in one ovarian MGSCTs showed amplification of 12p. All other germ cells were negative for amplification of 12p. All five successfully analyzed cases showed no mutation in all studied exons and exon-intron junctions in c-kit and PDFGRA genes.

Adult↗
PubMed2006

Phosphaturic mesenchymal tumor (mixed connective tissue variant): a case report with spectral analysis.

We present a further case of a rare mesenchymal neoplasm termed phosphaturic mesenchymal tumor (mixed connective tissue variant). The patient was a 42-year-old man with a long history of osteomalacia of unknown etiology with pathological bone fracture, abnormality of parathyroid glands, kyphosis, scoliosis, and spondylosis. Laboratory investigation disclosed hypophosphatemia, elevated serum alkaline phosphatase activity, and normal serum calcium level. The patient had a soft tissue mass in the right inguinal area, measuring 11 x 6 x 5 cm, which was previously interpreted as a calcified hematoma on sonography. The tumor was surgically removed. Grossly, the tumor was well circumscribed, unencapsulated, and had soft to dense consistency. The cut surface had a variegated appearance due to the presence of large hemorrhagic areas admixed with foci of grey-yellow tissue. Histologically, the tumor was composed of primitive mesenchymal cells, osteoclast-like cells, and cells showing myofibroblastic features without cytologic atypia. There were a well developed vascular network, microcystic areas, and poorly formed cartilaginous foci. Unusual and hitherto unpublished prominent features were flower-like, slate-gray crystals, widespread hemosiderin deposits and large areas of hemorrhages, with the latter comprising approximately 60% of the tumor. A spectral analysis indicated that chemically, the crystals mainly consisted of calcium phosphate and sodium nitrate.

Adult↗
PubMed2006

Oncocytic papillary renal cell carcinoma: a clinicopathologic, immunohistochemical, ultrastructural, and interphase cytogenetic study of 12 cases.

Papillary renal cell carcinoma (RCC) is subclassified in type 1 displaying cells with scanty pale cytoplasm arranged in a single layer and in type 2 showing pseudostratified cells with eosinophilic cytoplasm. However, the existence of more variants of papillary RCC may be inferred by the recognition of few cases with different morphological features. We report the clinicopathologic, immunohistochemical, ultrastructural, and interphase cytogenetic features of 12 papillary RCC composed by oncocytes. Ten patients were males and their median age was 67 years. The tumors were well demarcated and their median diameter was 7.1 cm. Solid oncocytoma-like areas occurred in 11 cases. The cytoplasm of the neoplastic cells was filled by mitochondria with lamellar cristae. All cases were positive for the antimitochondrial antigen and racemase and showed variable immunoreactivity for cytokeratins (AE1/AE3, CK8-18, CK7, CK19), EMA, CD10, vimentin, and parvalbumin. MIB1 was detected in 0 to 6 cells per 1 high-power field. Fluorescent in situ hybridization analysis on formalin-fixed paraffin-embedded tissue showed three or more signals for chromosome 7 and 17 (for both > or =30% of nuclei in 7 of 12 neoplasms). In males, signals of chromosome Y were absent in more than 80% of the neoplastic nuclei. One patient died of metastases. Interphase cytogenetic analysis by fluorescent in situ hybridization can be a diagnostic tool in cases mimicking an oncocytoma.

Adenoma, Oxyphilic↗
PubMed2006

High-grade urothelial carcinoma of the renal pelvis: clinicopathologic study of 108 cases with emphasis on unusual morphologic variants.

A clinicopathologic study of 108 cases of high-grade urothelial carcinomas of the renal pelvis is presented. Of the 108 tumors, 44 (40%) showed unusual morphologic features, including micropapillary areas (four cases), lymphoepithelioma-like carcinoma (two cases), sarcomatoid carcinoma (eight cases, including pseudoangiosarcomatous type), squamous differentiation and squamous cell carcinoma (15 cases), clear cells (two cases), glandular differentiation (two cases), rhabdoid, signet-ring or plasmacytoid cells (four cases), pseudosarcomatous stromal changes (four cases) and intratubular extension into the renal pelvis (three cases). Pathological staging was available in 62 patients; of these, 46 cases (74%) were in high stage (pT2-pT4) and 16 (26%) were in low stage (pTis, pTa, pT1). Clinical follow-up ranging from 1 to 256 months (median: 50 months) was available in 42 patients; of these, 26 (61%) died of tumor with a median survival of 31 months. The patients who did not die of their tumors showed only minimal or focal infiltration of the renal parenchyma by urothelial carcinoma, whereas those who died of their tumors showed massive infiltration of the kidney by the tumor. High-grade urothelial carcinomas of the renal pelvis can show a broad spectrum of histologic features similar to those seen in the urinary bladder. Our results support the finding that, unlike urothelial carcinomas of the bladder, the majority of primary urothelial carcinomas of the renal pelvis are of high histologic grade and present in advanced stages. Our study further highlights the fact that, in the renal pelvis, urothelial carcinomas show a tendency to frequently display unusual morphologic features and metaplastic phenomena. The importance of recognizing these morphologic variants of urothelial carcinoma in the renal pelvis is to avoid confusion with other conditions. The possibility of a high-grade urothelial carcinoma should always be considered in the evaluation of a tumor displaying unusual morphologic features in the renal pelvis, and attention to proper sampling as well as the use of immunohistochemical stains will be of importance to arrive at the correct diagnosis.

Adult↗
PubMed2006

Clear cell trichoblastoma: a clinicopathological and ultrastructural study of two cases.

Clear cell change in basal cell carcinomas is a well-recognized phenomenon, but is obviously rare in trichoblastomas. We present two cases of clear cell trichoblastoma in which clear cell change was very much prominent, and the results of an ultrastructural study intended to explore the basis of that feature. Both our patients were women, aged 56 and 77 years, who presented with solitary, slowly growing nodules that measured 3 to 5 cm in largest dimension and were located on the scalp and the flexor aspect of the lower arm. Microscopically, the tumors in both cases were symmetric, non-ulcerated, and composed of variably sized and shaped (cribriform, racemiform, strands, cords, nodules) aggregations of monomorphous basaloid epithelial cells that were associated with a specific trichogenic stroma. Common to both tumors was clear cell cytoplasm evident in the majority of the epithelial cells in one case and almost in the entire epithelial cell population in the other. In most epithelial aggregations the epithelial cells with clear cytoplasm often appeared columnar and were arranged in a palisade along a recognizable basal membrane, thus indicative of outer sheath differentiation at the bulb. There were other signs of follicular differentiation. Ultrastructurally, variably sized clusters of uniform small basaloid epithelial cells were separated from the stroma by a thin discontinuous basement membrane. In addition to the usual organelles, the cytoplasm contained fairly conspicuous tonofilaments and variably sized vacuoles devoid of a limiting membrane, located between the palisaded nuclei and the outer cell membrane. The majority of vacuoles were empty, although clumps of a finely granular substance were occasionally evident. No distinct lipid droplets or glycogen particles were identified. The basaloid cells were joined by scattered small desmosomes. These findings were consistent with trichilemmal differentiation at the bulb.

Aged↗
PubMed2006

Subcutaneous splenosis of the abdominal wall.

We report a case of subcutaneous splenosis in the abdominal wall of a 23-year-old oligophrenic man. It presented as a well-demarcated 8 x 7 x 5-cm subcutaneous tumor in the left inguinal area closely above the scar after a previous operation for hernia. The lesion simulated clinically a hernia or a tumor due to its large size and location and, additionally, no history could be taken from the patient due to his mental handicap.

Abdominal Wall↗
PubMed2006

Sclerotic (fibroma-like) lipoma: a distinctive lipoma variant with a predilection for the distal extremities.

This report details the clinicopathologic and immunohistochemical findings identified in 21 cases of a fibrosclerotic variant of lipoma from acral sites that is frequently misdiagnosed as a fibromatous (nonlipogenic) process. The study includes 12 males and 9 females; aged 7 to 72 (mean and median, 39). The patients presented with solitary, mostly asymptomatic, masses that ranged from 0.6 to 2.2 (median, 1.2; mean, 1.3) cm and involved fingers (n=17), hands or wrists (n=3), and toes (n=1). Microscopically, the lesions were well-circumscribed nodules that showed very low to moderately low cellularity and consisted of cytologically bland spindled and stellate-shaped cells and a minor component of randomly dispersed adipocytes embedded in a collagenous to myxocollagenous stroma. Eight tumors were "fibroma-like" owing to their paucity of spindled cells, dense fibrosclerotic stroma, and inconspicuous vasculature. One tumor showed features of spindle cell/pleomorphic lipoma, whereas another demonstrated a vague onion skin-like arrangement of collagen reminiscent of sclerotic (storiform) fibroma. In all cases, the mitotic activity was negligible. Nonlipogenic tumor cells were immunoreactive for CD99 (6 of 6 cases), CD34 (6 of 8), S-100 protein (4 of 7), and smooth muscle actin (2 of 6). Follow-up data on 8 patients (range, 1 to 20 years; median, 9.5 years) revealed no recurrence in 6, but indicated the possibility of persistent tumor in the remaining 2 individuals after simple excision. Despite histological overlap in 1 case with the sclerotic fibroma, no patient displayed definitive clinical features of Cowden syndrome. Our study indicates that fibrosclerotic lipomas demonstrate a broader histological scope than what was initially described.

Adolescent↗
PubMed2006

Low-grade adnexal carcinoma of the skin with multidirectional (glandular, trichoblastomatous, spiradenocylindromatous) differentiation.

The conjoint occurrence of follicular, sebaceous, or apocrine differentiations in a cutaneous adnexal neoplasm is a known event, more often encountered in benign neoplasms, whereas reports of cutaneous malignant adnexal tumors with bilineage or trilineage differentiation are few. A new case of a cutaneous malignant adnexal neoplasm with multidirectional differentiation is reported here. A 57-year-old woman presented with a long-standing, slowly growing, asymptomatic solitary tumor the size of a large nut in the coccygeal area, which was surgically excised. Ten years after the surgery, there was no evidence of recurrence or metastasis. Microscopically, the neoplasm was located in the dermis with focal extension into the subcutis. It was asymmetric, horizontally oriented, and mostly composed of small nodules that varied in shape from round and oval aggregations to elongated strands and irregular islands; the nodules were either clustered, formed a jigsaw puzzle-like pattern or were dispersed. The nodules were composed of small basaloid cells sometimes intermixed with larger cells with ample cytoplasm forming glandular structures. Rare nodules resembled elements seen in a spiradenoma by containing scattered lymphocytes and globules of hyalinized eosinophilic basal membrane material. The stroma was paucicellular, but focally it resembled that seen in perifollicular mesenchyme. Mitotic figures, including abnormal ones, were infrequent, but mild nuclear pleomorphism, nuclear crowding, and individual cell necrosis were easily appreciable in both small basaloid cells and cells with clear cytoplasm. Perineural invasion was apparent. We classified this tumor as a well-differentiated adnexal carcinoma demonstrating combined follicular and apocrine differentiation. It differs from previously published cases of malignant adnexal tumors with multidirectional differentiation and further exemplifies the spectrum of diversity encountered in malignant proliferations with differentiation toward the folliculosebaceous-apocrine unit.

Adnexal Diseases↗
PubMed2006

Minute synovial sarcomas of the hands and feet: a clinicopathologic study of 21 tumors less than 1 cm.

Synovial sarcoma, one of the most common types of soft tissue sarcomas, usually presents in the proximal or middle portions of the extremities, often as a large mass with an aggressive clinical behavior. Gland-forming biphasic and spindle cell fibrous monophasic tumors are the most common subtypes. In this study, we evaluated 21 minute synovial sarcomas, <1 cm in diameter, from the hands and feet. These tumors occurred in 14 females and 7 males with a median age of 29 years (range, 8-60 years). Clinically, all tumors were thought to be benign processes such as a ganglion cyst or glomus tumor, and on microscopic examination, they were also often initially misinterpreted as benign lesions such as nerve sheath or (myo) fibroblastic tumors. Histologically, 7 tumors were biphasic and 14 were monophasic spindle cell variants. Microscopic calcifications were present in 8 cases and were prominent in 3 tumors. All monophasic tumors tested had elements positive for EMA, and all but one had reactivity for a keratin cocktail. S-100 protein-positive neuroma-like neural proliferations were commonly present in the monophasic but not in biphasic tumors. SYT-SSX fusion transcripts were demonstrated in 5 cases studied by polymerase chain reaction assay. All tumors were enucleated, followed by local reexcision of the site, and often combined with postoperative radiation. Three patients had amputation of the involved digit or metatarsal. Four patients had local recurrences, 2 of which were successfully treated; 2 of these patients were lost to follow-up. Despite some variation in treatment, all 12 patients with complete follow-up were alive and well, 2 to 32.2 years after surgery (median, 14.7 years), including 2 patients who received neither amputation nor postoperative radiation. Minute synovial sarcomas of hands and feet are clinically favorable tumors if completely excised; there is some evidence to suggest that they may be managed more conservatively than larger tumors. These tumors should be recognized as part of the spectrum of synovial sarcomas.

Adult↗
PubMed2006

Clonal nature of sclerosing polycystic adenosis of salivary glands demonstrated by using the polymorphism of the human androgen receptor (HUMARA) locus as a marker.

Sclerosing polycystic adenosis (SPA) is a recently described, rare lesion of the salivary glands that bears a resemblance to epithelial proliferative lesions of the breast. The true nature of the lesion is unknown, but up to now it has been generally believed to represent a pseudoneoplastic sclerosing and inflammatory process. However, local recurrence developed in about one-third of the cases. Superimposed dysplastic changes ranging from low-grade dysplasia to carcinoma in situ were described in SPA. Although no metastases-related and/or disease-related patient deaths were documented, these clinical and histopathologic features raise the possibility that SPA might represent a neoplastic lesion. Polymorphism of the human androgen receptor locus is most frequently used to assess whether the pattern of X-chromosome inactivation is random or nonrandom, the latter strongly indicating clonality. In this study, the assay was applied to tissue from 12 examples of SPA. Three cases (males) were noninformative and 3 cases (females) could not be analyzed owing to poor quality of DNA, but all the remaining 6 lesions satisfied the criteria for monoclonality. We therefore conclude that the findings in the present study are further supporting evidence that SPA is a neoplasm, and not just a reactive process.

Adult↗
PubMed2006

Trichoepithelioma with giant and multinucleated neoplastic epithelial cells.

We report an unusual example of trichoepithelioma containing giant and multinucleated cells in the epithelial compartment. The patient was a 52-year-old woman who presented with a solitary nodule on the scalp measuring 2 cm of apparently long duration. The biopsy revealed a typical trichoepithelioma. The unusual feature was the presence in some epithelial nodules of large epithelial cells with hyperchromatic nuclei and no visible nucleoli that exceed 3 to 5 times the adjacent follicular germinative cells. Often, multinucleated cells were seen. Rare nodules were almost entirely composed of giant/multinucleated cells. The majority of the nodules containing giant cells were situated in the deeper portion of the neoplasm. No mitoses were seen in these giant cells. No enlarged or multinucleated cells were seen in the stroma. The neoplastic epithelial cells were diffusely reactive for bcl-2, including the giant and multinucleated cells. The proliferating rate was low; Ki-67 stained some giant cells. CD34 stained the stroma. We believe that the focal presence of pleomorphic giant cells in trichoepithelioma has no clinical or prognostic implications and does not denote its "malignant transformation".

Antigens, CD34↗
PubMed2006

Tubular adenoma of the skin with follicular and sebaceous differentiation: A report of two cases.

The main controversies regarding tubular apocrine adenoma and papillary eccrine adenoma are whether they are two distinct entities or are the very same tumor, and if so, which lineage of differentiation (apocrine versus eccrine) it pursues. We report two cases of tubular adenoma with follicular and, in one case, additionally, sebaceous differentiation. The features in both cases indicated apocrine differentiation of the tubular component. One patient was a 60-year-old woman with a 1-year history of a solitary nodule on the scalp. The other patient was a 48-year-old woman with a solitary nodule of unknown duration located on the back. In both patients, the tumors were surgically removed. The patients were alive and well 2.5 and 2 years after surgery, respectively. The histologic features that both cases had in common included the combination of a tubular adenoma, foci of follicular differentiation, and areas of immature squamous metaplasia. In case 1, follicular differentiation was seen in the form of strands of basaloid cells surrounded by a stroma resembling the embryonic perifollicular sheath. Some aggregates of basaloid cells were juxtaposed with small collections of plump fibroblasts, imparting a resemblance to rudimentary follicular germs associated with follicular papillae. Many minute lumens surrounded by more eosinophilic cells were seen within the strands. In case 2, follicular differentiation was seen as several infundibulocystic structures surrounded by isthmic epithelium housing scattered mature sebocytes. In addition, there were areas reminiscent of desmoplastic trichoepithelioma (columnar trichoblastoma). In both cases, the areas with immature squamous metaplasia were represented by solid nodules that were mostly devoid of lumens and a peripheral basal/myoepithelial cell layer. In conclusion, these two cases of cutaneous tubular adenoma with accompanying follicular and sebaceous differentiation give further support to the proposition that the majority of these neoplasms have apocrine differentiation. Rare cases occurring in the sites normally devoid of apocrine glands may represent the eccrine counterpart.

Adenoma↗
PubMed2006

Unusual hyperplasia of anogenital mammary-like glands.

Anogenital mammary-like glands, although known to exist (as ectopic breast tissue) as early as 1872, have only recently been thoroughly studied and suggested to be the possible origin for various neoplastic (benign and malignant) and reactive conditions that show a striking homology with lesions in the breast. Reported herein is an unusual benign lesion involving anogenital mammary-like glands in the perineal area of a 41-year-old woman. The lesion is unique in that it does not fully fit into any of the previously recognized conditions affecting anogenital mammary-like glands nor has it an apparent well-defined mammary counterpart. Microscopically, at first glance the lesion appeared as a cluster of extended anogenital mammary-like glands of variable complexity and a lobular architecture, which probably resulted from a compact proliferation of closely situated ducts with small, round lumens (when cut transversally). When cut longitudinally, some of these tiny ducts appeared to bud from larger ductal structures, resembling so-called satellitosis in the breast and this gave a fibroadenomatous appearance to the areas. In addition, there were adenosis-like areas. This lesion extends the spectrum of changes seen in anogenital mammary-like glands.

Actins↗
PubMed2006

Primary cutaneous lymphoproliferative disorders with dual lineage rearrangement.

We present a series of 15 cases of cutaneous lymphoma and pseudolymphoma with dual lineage rearrangement identified among approximately 1200 cases of cutaneous lymphoproliferative disorders assessed in our 4 institutions during the last 8 years in which the results of both T-cell receptor and immunoglobulin heavy chain rearrangement investigations were available. On the basis of the clinicopathologic information, the cases were retrospectively subdivided into 2 categories: (1) cases with definite features of cutaneous lymphoma or pseudolymphoma (n = 11) and (2) cases with unclassifiable disease (n = 4). The detection of dual genotype in the first group did not influence the final diagnosis; 7 cases represented cutaneous B-cell lymphomas, 3 pseudolymphomas, and 1 case lymphomatoid papulosis. The presence of monoclonal T-cell receptor-gene rearrangements in these cases may be explained either by monoclonal or oligoclonal expansion of exuberant T cells (or B cells in case of lymphomatoid papulosis) or by lineage infidelity. Three patients with unclassifiable disease had several clinical and histopathologic features in common. They were elderly, presented with solitary lesions, were in good general health and histopathologically demonstrated a dense multinodular infiltrate containing approximately an equal number of T and B cells and a high number of histiocytes forming granulomas, with prominent granulomatous features in 2 cases. B cells were either scattered with the infiltrate or formed collections vaguely resembling follicles; Reed-Sternberg-like cells were seen in 2 cases. B cells showed expression neither of immunoglobulin light chain. The T-cell component was represented mainly by small, well-differentiated lymphocytes or slightly pleomorphic cells, with some medium-sized convoluted cells. Epstein-Barr virus was not detected by polymerase chain reaction. The exact classification of these cases is unknown; they differ histopathologically from previously published cases of bigenotypic cutaneous lymphomas. They may merely represent a growth or reactive pattern, but, on the other hand, may be low-grade lymphomas. If so, they may be histopathologically related to cutaneous Hodgkin disease, T-cell/histiocyte-rich large B-cell lymphoma, or composite lymphomas. Further reports are needed to identify these lesions to clarify their nature and biologic potential.

Adult↗