Dermatopathology in sub-Saharan Africa: a systematic 5-year analysis of all histopathological diagnoses from the Regional Dermatology Training Centre (RDTC) in Moshi, Tanzania.

BACKGROUND Proper diagnosis of skin diseases relies on dermatopathology, the most important diagnostic technique in dermatology. Unfortunately, there are few dermatopathology institutions in sub-Saharan Africa, where little is known about the spectrum of histopathological features observed. OBJECTIVES To investigate the spectrum of dermatopathological diagnoses made in a sub-Saharan African reference centre of a large, mainly rural area. PATIENTS/METHODS To retrospectively evaluate all dermatopathological diagnoses made over a period of 5 years at the Regional Dermatology Training Centre (RDTC) in Moshi, Tanzania. RESULTS There were a total of 1554 skin biopsy specimens. In 45% of cases, there were inflammatory diseases, most frequently lichenoid conditions. Cutaneous neoplasms represented 30.4% of all diagnoses, with Kaposi's sarcoma (KS) and, less frequently, squamous cell carcinoma (SCC) being the two most common neoplastic conditions. The latter also reflected the intensive management of persons with albinism in the RDTC. The distribution of histological diagnoses seemed to correlate with the overall clinical spectrum of cutaneous diseases managed in the RDTC. CONCLUSIONS In this African study inflammatory conditions are the main burden of skin diseases leading to a diagnostic biopsy. Our findings provide further evidence that KS, primarily related to the high prevalence of HIV infection is an epidemiological problem. Both SCC and basal cell carcinoma represent another relatively common malignant cutaneous neoplasms, reflecting the presence of specific populations at risk. The challenging spectrum of histological diagnoses observed in this specific African setting with basic working conditions shows that development of laboratory services of good standards and specific training in dermatopathology are urgently needed.

The use of special stains at two dermatopathology laboratories in East Africa.

BACKGROUND Histopathology is often essential to establish an accurate diagnosis. Pathology laboratories are scarce in most Sub-Saharan Africa where dermatopathology is a developing field. In resource-poor countries, most specimens are analyzed only after hematoxylin and eosin staining. The availability of special stains is very limited and restricted to only few centers. The aim of this study is to analyze the extent of dermatopathological cases which can be adequately diagnosed after hematoxylin and eosin alone. Secondly, to investigate which cases required further special stains. METHODS All skin specimens submitted to two University Hospitals (Tanzania and Kenya) were included in this study. All specimens were first analyzed with hematoxylin and eosin and a diagnosis established when possible. All cases in which an accurate diagnosis after hematoxylin and eosin only was not possible, were registered and evaluated after further special stains. RESULTS A total of 386 specimens were examined. A proper histopathologic diagnosis with hematoxylin and eosin alone was possible in 344 (89.1%) samples. In 45 (11.6%) cases, mostly skin infections, further special stains were necessary. CONCLUSION A proper histopathologic diagnosis was possible after hematoxylin and eosin alone in almost 90% of the specimens submitted to the two laboratories in Sub-Saharan Africa.

Primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma: a cutaneous nodular proliferation of pleomorphic T lymphocytes of undetermined significance? A study of 136 cases

Patients with skin nodules characterized by the infiltrate of pleomorphic small/medium T lymphocytes are currently classified as "primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma" (SMPTCL) or as T-cell pseudolymphoma. The distinction is often arbitrary, and patients with similar clinicopathologic features have been included in both groups. We studied 136 patients (male:female = 1:1; median age: 53 years, age range: 3-90 years) with cutaneous lesions that could be classified as small-/medium-sized pleomorphic T-cell lymphoma according to current diagnostic criteria. All but 3 patients presented with solitary nodules located mostly on the head and neck area (75%). Histopathologic features were characterized by nonepidermotropic, nodular, or diffuse infiltrates of small- to medium-sized pleomorphic T lymphocytes. A monoclonal rearrangement of the T-cell receptor-gamma gene was found in 60% of tested cases. Follow-up data available for 45 patients revealed that 41 of them were alive without lymphoma after a median time of 63 months (range: 1-357 months), whereas 4 were alive with cutaneous disease (range: 2-16 months). The incongruity between the indolent clinical course and the worrying histopathologic and molecular features poses difficulties in classifying these cases unambiguously as benign or malignant, and it may be better to refer to them with a descriptive term such as "cutaneous nodular proliferation of pleomorphic T lymphocytes of undetermined significance," rather than forcing them into one or the other category. On the other hand, irrespective of the name given to these equivocal cutaneous lymphoid proliferations, published data support a nonaggressive therapeutic strategy, particularly for patients presenting with solitary lesions.

Melan-a-positive "pseudomelanocytic nests": a pitfall in the histopathologic and immunohistochemical diagnosis of pigmented lesions on sun-damaged skin

We encountered recently 3 cases with a histopathologic diagnosis of melanoma in situ on sun-damaged skin (male = 2, female = 1; median age: 59 years; range: 52-60 years). The diagnosis was based mainly on the finding of actinic elastosis in the dermis and increased number of melanocytes in the epidermis and was confirmed by strong positivity for Melan-A in single cells and in small nests ("pseudomelanocytic nests"), located at the dermoepidermal junction. Indeed, examination of slides stained with hematoxylin and eosin revealed the presence of marked hyperpigmentation and small nests of partially pigmented cells at the dermoepidermal junction, positive for Melan-A. The histologic and especially the immunohistochemical features were indistinguishable from those of melanoma in situ on chronic sun-damaged skin. In addition, a variably dense lichenoid inflammation was present. Clinicopathologic correlation, however, showed, in all patients, the presence of a lichenoid dermatitis (phototoxic reaction, 1 case; lichen planus pigmentosus, 1 case; and pigmented lichenoid keratosis, 1 case). Our cases clearly show the histopathologic pitfalls represented by lichenoid reactions on chronic sun-damaged skin. Immunohistochemical investigations, especially if performed with Melan-A alone, may lead to confusing and potentially disastrous results. The unexpected staining pattern of Melan-A in cases like ours raises concern about the utility of this antibody in the setting of a lichenoid tissue reaction on chronic sun-damaged skin. It should be underlined that pigmented lesions represent a paradigmatic example of how immunohistochemical results should be interpreted carefully and always in conjunction with histologic and clinical features.

Supraorbital cutaneous fetal rhabdomyoma of intermediate type: a case report.

A 7-year-old boy was presented with a long-standing slowly growing mass of the left supraorbital area. A biopsy specimen revealed a bland spindle cell proliferation with scattered polygonal cells with acidophilic cytoplasm and cross-striations. Our differential diagnosis included rhabdomyoma of fetal type, leiomyoma with trapping of regenerating skeletal muscle elements, and rhabdomyomatous mesenchymal hamartoma of the skin. Immunohistochemistry demonstrated strong positivity of myoglobin and desmin as well as negativity of caldesmon, suggesting skeletal muscle lineage. The excisional specimen confirmed our diagnosis of cutaneous fetal rhabdomyoma of intermediate type. Additional immunostaining performed on the excisional specimen showed strong Wilms Tumor 1 but only a very faint and focal p63 expression.

Angiomatous kaposi sarcoma: a variant that mimics hemangiomas.

We describe 14 cases of angiomatous Kaposi sarcoma (KS), a distinct histological variant of KS first mentioned by Gottlieb and Ackerman in 1988 that can easily be mistaken for a hemangioma. Intriguingly, this variant of KS has not attracted much attention and has not been studied in detail. Immunohistochemistry showed prominent staining of podoplanin (D2-40) of the neoplastic vasculature but not the preexisting vessels, suggesting lymphatic differentiation, despite the erythrocyte-filled round lumens. To test whether D2-40 staining of round vessels with erythrocytes was distinctive, we stained sinusoidal hemangiomas and cellular angiolipomas, both of which have these structures. In contrast to angiomatous KS, the vessels in both entities were podoplanin (D2-40) negative. The finding of round erythrocyte-filled vessels with podoplanin (D2-40) positivity may be distinctive for this form of KS.

Prognostic Implication of Lymphovascular Invasion Detected by Double Immunostaining for D2-40 and MITF1 in Primary Cutaneous Melanoma.

BACKGROUND Lymphovascular invasion (LVI) is associated with adverse outcomes in primary cutaneous melanoma (PCM). Detection of LVI by hematoxylin and eosin staining alone is 0%-6%, but targeting lymphovascular structures increases the detection rate. OBJECTIVE To examine the prognostic significance of LVI detected by immunostaining for D2-40 and microphthalmia-associated transcription factor 1 (MITF1) in PCM. METHODS The authors retrospectively analyzed 120 PCM samples. We compared the LVI detection rates of immunostaining for D2-40 only (22%), double staining for D2-40 and MITF1 (38%), and hematoxylin and eosin, and examined the association of LVI with clinicopathologic variables and clinical outcomes. RESULTS Immunolabeling with both methods significantly increased the LVI detection rate. Double staining for D2-40 and MITF1 as well as D2-40-detected LVI was significantly associated with increased Breslow thickness, number of mitoses, and sentinel lymph node (SLN) metastasis. D2-40-detected LVI was also associated with ulceration. Although the difference was not significant, double staining for D2-40 and MITF1 allowed for easier detection of LVI than D2-40 alone. LIMITATIONS This study was conducted in a tertiary referral institution; therefore, a referral bias cannot be excluded. CONCLUSIONS Immunolabeling increased detection of LVI in PCM. Because LVI is a positive predictive marker for SLN metastasis, the authors propose using anti-D2-40 and anti-MITF1 in the evaluation of LVI in patients with PCM with a certain risk of SLN metastasis.