Indeterminate cell histiocytosis: fact or fiction?

Abstract: Indeterminate cell histiocytosis is a rare disorder, in which the predominant cells have the characteristics of both Langerhans cells and macrophages. We, in this study, describe 18 patients and compare them with those previously published. Most patients were adults with either solitary or multiple red‐brown papules or nodules. While most lesions were confined to the skin, both conjunctival and bony involvement was seen. Histologically, the lesions showed patterns resembling those described for xanthogranulomas, with predominantly oncocytic (nine patients), spindled (five patients), scalloped (two patients) or vacuolated (two patients) macrophages. The accompanying infiltrate was mainly lymphocytic, although eosinophils and occasionally plasma cells were seen. All lesions were positive for macrophage markers, such as KP1 (CD68) and Ki‐M1p, as well as for S‐100 protein and showed variable reactivity for CD1a. No Birbeck granules were seen ultrastructurally in one patient. Some patients shared features with sinus histiocytosis with massive lymphadenopathy. It is unclear whether this disorder is a separate entity or represents various macrophage disorders identified at various time points in the inflammatory response.     

Giant cell angiofibroma or localized periorbital lymphedema?

Giant cell angiofibroma represents a rare soft tissue neoplasm with a predilection for the orbit. We recently encountered a mass removed from the lower eyelid of a 56‐year‐old female that histopathologically resembled giant cell angiofibroma. The process consisted of haphazardly arranged CD34‐positive spindled and multinucleated cells within an edematous, densely vascular stroma. However, the patient had recently undergone laryngectomy and radiotherapy for a laryngeal squamous cell carcinoma. A similar mass had arisen on the contralateral eyelid, and both had developed several months post‐therapy. Lymphedema of the orbit can present as tumor‐like nodules and in some cases may share histopathologic features purported to be characteristic of giant cell angiofibroma. A relationship between giant cell angiofibroma and lymphedema has not been established, but our case suggests there may be one. The potential overlap of these two conditions should be recognized, as should other entities that may enter the differential diagnosis.     

Nevoid basal cell carcinoma syndrome or multiple hereditary infundibulocystic basal cell carcinoma syndrome?

We present a case of nevoid basal cell carcinoma syndrome, also known as Gorlin syndrome, or basal cell nevus syndrome, which clinically follows a course more consistent with multiple hereditary infundibulocystic basal cell carcinomas or multiple hereditary trichoepitheliomas. The following article describes the case in detail and gives an overview of other genodermatosis, which were initially considered in the differential and which may be linked pathogenetically.     

Nevus marginatus: a distinct type of epidermal nevus or merely a variant of nevus sebaceus?

Epidermal nevi (EN) represent a heterogeneous group of mosaic skin lesions frequently following the lines of Blaschko. They are divided into organoid and nonorganoid types. Herein we report on a 35-year-old man with a rather unusual type of EN. A linear lesion involving the trunk and following Blaschko's lines was conspicuously bordered by dark brown papules. The flat reddish central area histopathologically showed sebaceous hyperplasia consistent with nevus sebaceus, an organoid EN type, whereas the elevated margin showed features of a common nonorganoid keratinocytic EN. For this peculiar disorder, we propose the term 'nevus marginatus'. So far it is not clear whether nevus marginatus represents a distinct entity or merely an unusual clinical variant of nevus sebaceus.     

Spontaneous regression of renal cell carcinoma: Reality or myth?

Spontaneous regression of a malignant tumor is a very rare phenomenon.Renal cell carcinoma(RCC)is an aggressive malignancy with an often unpredictable behaviour.The incidence of spontaneous regression in metastatic RCC has been estimated to lie between1%and 7%.The spontaneous regression of a primary RCC has been reported much less commonly.Our literature review assesses the published literature concerning spontaneous regression of either primary or metastatic RCC.In order to examine this phenomenon in more detail we performed a literature search in the Pub Med Database using the Keywords"renal cell carcinoma","metastatic disease",and"spontaneous regression"and included reports from the last100 years.The incidence of spontaneous regressions in RCC has always been considered a special feature of RCC compared to other solid malignancies.The majority of case reports of spontaneously regressed RCC describe the regression of metastases after nephrectomy rather than the spontaneous regression of a primary tumor.In cases of reported regression of metastatic RCC,this mostly applied to pulmonarylesions.As possible reasons for spontaneous regressions host immune defense mechanisms against metastatic RCC tissue following nephrectomy are discussed as important factor.RCC is known to be highly immunogenic and the possible existence of cytotoxic serum factors and tumor-specific surface antigens may trigger a cell-mediated cytotoxicity as an immunological basis for regression.Histological verification of supposed regression of a primary tumor may cause diagnostic difficulties,since large central areas of necrosis and cystic lesions of the tumor can occur simultaneously.The well-known phenomenon of necrosis in a fast growing RCC at the time of nephrectomy must not be confused with true spontaneous regression.Therefore,in our opinion such reported cases of supposed partial spontaneous regressions of primary RCCs are highly questionable.Most cases of spontaneous regression of RCC metastases have been reported after nephrectomy as the only treatment.Debulking by tumor nephrectomy then gives the immune system the chance to cope effectively with the remaining much lower quantity of tumour antigens.However,the mechanisms leading to spontaneous regression of metastatic lesions after cytoreductive nephrectomy are still poorly understood.     

Nevus anelasticus: how should such lesions be classified?

Nevus anelasticus represents a rare entity that is most commonly classified as a connective tissue nevus. It typically presents before 20 years of age with asymmetrically distributed white‐to‐skin‐toned or pink‐to‐red papules or plaques on the trunk and upper extremities. The lesion is defined histopathologically by the absence or degeneration of elastic fibers in the dermis. We report the case of a healthy 17‐year‐old female who presented with an asymptomatic slowly progressive plaque on the right inferior areola. Histopathologic examination showed the absence of elastic fibers in the papillary and upper reticular dermis and fragmented elastic tissue fibers in the deep reticular dermis. Although there is ongoing controversy regarding the nosology of this uncommon disorder, we propose that it is a distinct entity based on its histopathologic and clinical features.     

Merkel cell tumor in a trichilemmal cyst: collision or association?

An 86-year-old white male presented with an erythematous, painless, slowly growing, and firm left thigh nodule. Histologic examination revealed a dermal proliferation of monomorphous cells arranged in trabeculae, nests, and sheets with an infiltrative growth pattern. The cells had a high nuclear-cytoplasmic ratio, finely granular nuclear chromatin, and nuclear molding. Numerous mitotic figures, apoptotic cells, and individual cell necrosis were present; lymphovascular invasion was identified. The tumor was attached, demonstrating pagetoid intraepithelial migration, to a follicular cyst lined by squamous epithelium, lacking a granular cell layer and filled with compact keratinous content, diagnostic of trichilemmal cyst. Immunohistochemical study revealed that tumor cells expressed pan-cytokeratin (CK), chromogranin, synaptophysin, neuron-specific enolase, and CK20 (dotlike staining pattern), thus supporting the diagnosis of Merkel cell carcinoma. The association of Merkel cell carcinoma with a cyst is an exceptionally rare occurrence. As a result of the prominent involvement of the cyst wall by tumor cells, we favor that in this case carcinoma arose in the trichilemmal cyst rather than being a collision tumor. This hypothesis is also supported by the recent observation that Merkel cells are frequently present within normal hair follicles, especially in the isthmic portion that corresponds with the area of origin of the trichilemmal cyst.     

What's your assessment? Psoriasis with steroid atrophy

The "What's Your Assessment?" series includes a short case presentation and differential diagnosis. It is followed by a discussion of the disease or condition and the rationale used in each step of the assessment.     

Congenital spindle cell naevus with unusual transformation: proliferative nodule or melanoma?

Congenital melanocytic naevi can give rise to secondary melanocytic tumours, such as proliferative nodules and malignant melanoma. The clinical and histological features of both lesions may be nearly identical, which makes an unequivocal diagnosis impossible. In particular, it is difficult to differentiate clearly between benign and malignant proliferation in infants with secondary melanocytic proliferation. Reports on melanocytic proliferation and malignant melanoma within the paediatric age-group are very rare. There is limited expert knowledge on this subject and little is known about prognosis and outcome. We report here a case of an infant with an unusual transformation of a congenital spindle cell naevus of the umbilical region, and discuss clinical, histological and genomic criteria.