Tumor of follicular infundibulum is Basal cell carcinoma.

Tumor of follicular infundibulum (TFI) is currently thought to be a benign epithelial neoplasm with follicular differentiation. It is encountered commonly in association with basal cell carcinoma (BCC), often as an incidental finding. We reexamined 24 cases of TFI and noted, often only focally, many changes typical of BCC, including palisading of cells at the periphery of aggregations, germinative cells, follicular germs in the absence of a follicular papilla, crowding of cells, individual necrotic neoplastic cells, fibromucinous stroma, and clefts between aggregations of neoplastic cells and stroma. Five cases were associated with BCC, and 2 of them showed obvious continuity between both types of lesions. Moreover, we observed recurrences of what seemed to be a completely removed BCC in which tiny columns of cells typical of TFI were present in surgical margins. Those findings prompted us to conclude that TFI may be one of many manifestations of BCC rather than a differential diagnosis of it.

Mycosis fungoides mimicking erysipelas.

Mycosis fungoides may rarely simulate facial erysipelas. In a patient with that clinical presentation, a biopsy specimen revealed a diffuse dermal infiltrate with numerous neutrophils that also mimicked erysipelas histopathologically. The diagnosis of mycosis fungoides was made on the basis of atypical lymphocytes with focal epidermo- and folliculotropism. It was confirmed by typical findings of mycosis fungoides in a second biopsy from a clinically inconspicuous patch. An identical T-cell receptor gamma-gene rearrangement was detected in lymphocytes of both biopsy specimens.

Follicular squamous cell carcinoma of the skin: a poorly recognized neoplasm arising from the wall of hair follicles.

BACKGROUND: In the last decades, a number of clinicopathologic subtypes of squamous cell carcinoma (SCC) of the skin, ranging from highly aggressive tumors with a tendency to recur and metastasize to neoplasms with a favorable prognosis, have been described. SCCs arising from the wall of hair follicles have been briefly mentioned by some authors but never reported in a series. METHODS: Cases of SCC arising from the wall of hair follicles were collected from the files of two large German Centers for Dermatopathology and analyzed clinicopathologically and immunohistochemically. RESULTS: Sixteen cases of SCC developing in hair follicles were found among more than 7000 cases of cutaneous SCC reviewed. In most cases, tumors arose on sun-damaged skin of the face of elderly persons. There was a male predominance (11/5). The most common clinical diagnosis was basal cell carcinoma (BCC). Microscopically, tumors developed in the upper part of hair follicles without or with focal involvement of the overlying epidermis at the border with the involved follicle. Immunohistochemically, tumors were positive for cytokeratin and negative for a battery of immunomarkers, including antibodies against the most common carcinogenic human papillomaviruses (HPV) of the skin. Most tumors were excised by simple excision. In two cases, a recurrence was noted after incomplete excision. No further recurrences or metastasis have been noted after a follow-up period ranging from 11 months to 12 years. CONCLUSION: SCC of the hair follicle represents a poorly recognized but distinctive subset of SCC of the skin that should be considered in the differential diagnosis of other cutaneous epithelial tumors. The term follicular SCC (FSCC) is proposed for this neoplasm.

Erythema annulare centrifugum: results of a clinicopathologic study of 73 patients.

Erythema annulare centrifugum is classified generally into a superficial and a deep type. Whether those types are variants of the same process or unrelated to one another, and whether they represent non-specific patterns or specific clinico-pathologic entities, is controversial. To answer those questions, we analyzed 82 biopsy specimens from 73 patients with a clinical and histopathologic diagnosis of erythema annulare centrifugum, gyrate erythema, or figurate erythema regarding a variety of clinical and histopathologic findings. We found substantial differences between cases with a wholly superficial type and cases with a superficial and deep infiltrate. Clinically, a collarette of scales was seen only in the superficial type. Histopathologically, some findings were much more common in the superficial type (eg, spongiosis, parakeratosis, crusts, edema of the papillary dermis, epidermal hyperplasia) and others in the deep type (eg, sleeve-like arrangement of the infiltrate, melanophages, subtle vacuolar changes at the dermo-epidermal junction, individual necrotic keratinocytes). Whereas cases of the superficial type could be distinguished from differential diagnoses by a variety of clinical and histopathologic findings, most cases of the deep type showed subtle signs of lupus erythematosus. Neither type was associated consistently with any other systemic disease. Because the superficial and the deep type of erythema annulare centrifugum seem to be unrelated to one another, they should not be referred to by the same name. We believe that the term should be reserved for the superficial type because the latter seems to be a specific clinico-pathologic entity. By contrast, most cases of the deep type seem to be annular examples of tumid lupus erythematosus and should be diagnosed that way. If findings militate against the diagnosis of lupus erythematosus, we suggest using a descriptive term that signals non-specificity-namely, deep figurate erythema.

Fibroblastic/myofibroblastic sarcoma of the skin: a report of five cases.

BACKGROUND: A number of malignant soft tissue tumors, particularly those of fibroblastic and fibrohistiocytic derivation, have been found to display myofibroblastic differentiation focally. The term myofibroblastic sarcoma, a controversial presumably distinctive entity, defines a malignant soft tissue tumor in which myofibroblasts are quantitatively the predominant cell type. METHODS: Five cases of cutaneous spindle-cell sarcomas showing fibroblastic-myofibroblastic differentiation with predominance of fibroblasts were retrieved from the files of three large centers of dermatopathology. Tumors were analyzed histopathologically, immunophenotypically, and, in two cases, ultrastructurally. Results were compared with those previously reported in fibrosarcoma, malignant fibrous histiocytoma, and myofibroblastic sarcoma. RESULTS: Immunophenotypic and ultrastructural profiles of the cases analyzed in this series were closer to fibrosarcoma and to malignant fibrous histiocytoma than to myofibroblastic sarcoma by virtue of quantitative predominance of fibroblasts over myofibroblasts. On the other hand, histopathologic findings were in keeping with those reported in myofibroblastic sarcoma. CONCLUSIONS: Our series highlights the intrinsic problems in attaching certain cutaneous sarcomas with fibroblastic-myofibroblastic differentiation to one of the recognized entities and gives support to the hypothesis that fibrosarcoma, malignant fibrous histiocytoma, and myofibroblastic sarcoma are related histogenetically.

Pigmented atypical fibroxanthoma: a tumor that may be easily mistaken for malignant melanoma.

Nine cases of an unusual presentation of atypical fibroxanthoma that we previously termed pigmented atypical fibroxanthoma are reported. Pigmented atypical fibroxanthoma can be easily mistaken for malignant melanoma both clinically and histopathologically. The resemblance of pigmented atypical fibroxanthoma to melanoma is secondary to the ability of neoplastic cells to ingest and degrade erythrocytes following intratumoral hemorrhage and to accumulate hemosiderin in their cytoplasm. The histopathologic diagnosis of pigmented atypical fibroxanthoma can be easily confirmed by immunohistochemistry and iron stain.

Balanitis of Zoon: a clinicopathologic study of 45 cases.

Balanitis of Zoon is a relatively common diagnosis in elderly men, although its nature is controversial and descriptions of its histopathologic features in current textbooks of dermatopathology vary considerably. We studied 45 cases of balanitis of Zoon clinically and histopathologically. The earliest histopathologic changes in cases diagnosed clinically as balanitis of Zoon were slight thickening of the epidermis, parakeratosis, and a patchy lichenoid infiltrate of lymphocytes and some plasma cells. More advanced cases showed atrophy of the epidermis, superficial erosions, a scattering of neutrophils in the upper reaches of the epidermis, scant spongiosis, extravasation of erythrocytes, and a much denser infiltrate with many plasma cells. Additional findings at even later stages were subepidermal clefts, sometimes with loss of the entire epidermis, marked fibrosis of the superficial dermis, and many siderophages. That sequence of histopathologic changes is compatible with the thesis that balanitis of Zoon results from irritation or mild trauma affecting barely keratinized skin in a moist environment. As a reaction to nonspecific stimuli, balanitis of Zoon may be found superimposed on lesions of other diseases and may modify the histopathologic presentation of those diseases to the extent that they are no longer recognizable. In the current study, several cases diagnosed originally as balanitis of Zoon turned out to be examples of allergic contact dermatitis, psoriasis, lichen planus, and squamous cell carcinoma in situ. It is important, therefore, to recognize balanitis of Zoon as a nonspecific pattern that may occur either as an isolated finding or may complicate other diseases affecting the glans penis or prepuce of uncircumcised men.

Malignant fibrous histiocytoma of the skin with marked inflammatory infiltrate: a sarcoma mimicking malignant lymphoma.

Three cases of malignant fibrous histiocytoma of the skin with a marked inflammatory infiltrate in the stroma are reported. The inflammatory infiltrate, composed mainly of T-lymphocytes, obscured the nature of the neoplasms, and immunohistochemical studies were required to establish the diagnosis. Two tumors arose in the sun-damaged skin of the face, and one tumor arose in the chest wall. One patient developed a local recurrence with histopathologic findings similar to those observed in the original lesion, including the inflammatory infiltrate. Possible differential diagnoses include large cell lymphoma, inflammatory pseudotumor, inflammatory leiomyosarcoma, and spindle cell squamous cell carcinoma. The presumed rarity of inflammatory changes in malignant fibrous histiocytoma of the skin is supported by the absence of reported cases.

[Plasma-cell granuloma of the kidney pelvis]. / Granuloma de células plasmáticas de la pelvis renal.

OBJECTIVE: To report a rare case of plasma cell granuloma of the renal pelvis. To our knowledge, only five cases have been reported in the literature. METHODS: Clinicopathological description of a case of plasma cell granuloma of the renal pelvis with light chain immunohistochemical study. RESULTS: A young male patient with a radiologically benign mass in the right renal pelvis extending into the upper calices that caused hematuria is described. The diagnosis was suggested during the intraoperative study of the mass that was suggested by pyelotomy (conservative surgery). Immunohistochemical study confirmed the initial diagnosis. CONCLUSIONS: Although this condition is rare, plasma cell granuloma, an inflammatory pseudotumor, can occur in the urinary tract and should be considered in the differential diagnosis of mass lesions. Histopathological diagnosis requires a complete study of the entire tumor and the use of immunohistochemical techniques to discard plasmacytic non-Hodgkin lymphoma or neoplastic plasma cell proliferation.

Subcutaneous pseudomembranous fat necrosis: new observations.

BACKGROUND: Pseudomembranous fat necrosis is a peculiar manifestation of necrosis of adipose tissue characterized by formation of pseudocystic cavities lined by crenulated membranes. The underlying mechanism for the formation of pseudomembranes is unknown and numerous hypotheses have been proposed. Despite divergent interpretations, most authors consider necrotic fat cells to be the anatomic substrate for the formation of pseudomembranes. METHODS: A total of 341 panniculitides were reviewed for the presence of pseudomembranous fat necrosis. The specific diagnoses were established after correlation of all available clinical and laboratory data with the histopathology. Special attention was given to the time in the evolution of the disease when the biopsy was taken. Additional immunohistochemical studies were performed in 12 cases. RESULTS: Thirty of 341 cases of different types of panniculitides were found to show pseudomembranous fat necrosis, namely: 10 of 15 cases of sclerosing panniculitis (lipodermatosclerosis), 6 of 95 cases of erythema nodosum, 7 of 34 cases of traumatic panniculitis, 1 of 7 cases of lupus panniculitis, 1 of 20 cases of erythema induratum Bazin (nodular vasculitis), 1 of 9 cases of necrobiosis lipoidica, 1 of 4 cases of sclerotic lipogranuloma, 1 of 9 cases of infectious panniculitis (erysipelas), 1 of 2 cases of pancreatic panniculitis, and 1 of 4 cases of subcutaneous sarcoidosis. Pseudomembranous fat necrosis labelled strongly for the histiocytic markers CD68 and lysozyme. CONCLUSIONS: Our series provides data suggesting that pseudomembranous fat necrosis represents a dynamic process that varies according to the evolution of the lesion at the time of the biopsy. In biopsies taken from early foci of panniculitides pseudomembranes show vescicular or picnotic nuclei. Later, pseudomembranes retain their crenulated appearance but lack nuclear elements. Furthermore, we present histopathologic, histochemical, and immunohistochemical evidence that pseudomembranous fat necrosis results from the interaction of residual products of disintegrated fat cells and macrophages. Histiocytic markers such as CD68 and lysozyme may be used as reliable tools in order to detect pseudomembranes in panniculitides.

Granuloma de células plasmáticas de la pelvis renal / Plasma cell granuloma of the renal pelvis

OBJETIVOS: Reseña de un caso de granuloma de células plasmáticas de la pelvis renal. Los granulomas de células plasmáticas del tracto urinario son muy raros y sólo se han descrito cinco casos.MÉTODO: Descripción clínico-patológica de un caso de granuloma de células plasmáticas de pelvis renal con estudio inmunohistoquímico de cadenas ligeras.RESULTADO: Se trataba de un paciente varón joven con una masa radiológicamente benigna en pelvis renal derecha, que se extendía al grupo calicial superior y causaba hematuria total. El diagnóstico se sugirió por estudio intraoperatorio de la lesión resecada por pielotomía, lo que permitió un tratamiento conservador. El estudio inmunohistoquímico diferido confirmó el diagnóstico inicial.CONCLUSIÓN: Aunque muy infrecuente, el granuloma de células plasmáticas, que se incluye en el grupo de los pseudotumores inflamatorios, puede afectar a las vías urinarias y ha de considerarse en el diagnóstico diferencial de las neoplasias. Se trata de un diagnóstico histopatológico que requiere el estudio completo de toda la tumoración y la utilización de técnicas inmunohistoquímicas para descartar linfoma no Hodgkin de tipo plasmacítico o proliferación plasmocelular neoplásica (AU)