Histologic features of alopecia areata other than peribulbar lymphocytic infiltrates.

BACKGROUND: Histologic features other than a lymphocytic infiltrate around follicular bulbs are now recognized as helpful clues to the diagnosis of alopecia areata, especially in long-standing lesions where the peribulbar lymphocytic infiltrate may be sparse or absent. OBJECTIVES: We sought to determine the frequency of peribulbar lymphocytic infiltrates, eosinophils, lymphocytes, and melanin in fibrous tracts, pigment casts in follicles, the presence of catagen/telogen follicles, follicular miniaturization, and dystrophic ("nanogen") follicles in alopecia areata. Secondly, we sought to compare the diagnostic use of transversely sectioned versus horizontally sectioned specimens in those cases for which both were available (15 of 109 cases). METHODS: The pathology archives of Geisinger Medical Center (Danville, PA), Wilford Hall US Air Force Medical Center (San Antonio, TX), and Brooke US Army Medical Center (San Antonio, TX) were searched for the term "alopecia areata" in the diagnostic field from the period of 1991 to 2006, which yielded 109 cases with sections suitable for review. Cases from the two military institutions from 1997 or earlier were excluded to avoid any overlap with data previously reported by our group. RESULTS: A peribulbar lymphocytic infiltrate was present in 92 specimens (84%), eosinophils in fibrous tracts in 48 (44%), lymphocytes in fibrous tracts in 102 (94%), melanin within fibrous tracts in 92 (84%), pigment casts within follicular canals in 46 (44%), catagen follicles in 101 (93%), and miniaturized follicles in 98 (90%). Dystrophic miniaturized follicles were rare (4 cases). In 14 of 15 cases with both vertical and transverse sections, either was diagnostic. One case showed diagnostic features only in vertical sections. LIMITATIONS: Comparable vertical and transverse sections were only available for a limited number of the cases. We did not correlate duration of disease with individual findings. Our results were correlated with the clinical diagnosis but not with serologic tests for syphilis. CONCLUSIONS: Although most specimens showed evidence of a peribulbar lymphocytic infiltrate (84%), a higher percentage showed evidence of follicles in catagen/telogen phase (93%) and evidence of miniaturization of follicles (90%). This could lead to an incorrect diagnosis of trichotillomania or pattern alopecia. Pigment casts within the hair canal were also found in a significant number of follicles, especially in catagen follicles, creating further potential for misdiagnosis as trichotillomania. A significant percentage showed evidence of eosinophils (44%), melanin (84%), and lymphocytes (94%) in fibrous tracts. These features are particularly helpful when a peribulbar lymphocytic infiltrate is lacking. Vertical and transverse sections appear comparable.

Is superficial spreading melanoma still the most common form of malignant melanoma?

BACKGROUND: Most epidemiological studies suggest that superficial spreading melanoma is the most common histological subtype of malignant melanoma, but past data may not reflect current patterns of sun exposure or other risk factors. OBJECTIVE: We sought to determine the prevalence of melanoma subtypes among recent specimens in a South Texas dermatopathology practice. RESULTS: Lentigo maligna was the most common subtype of melanoma among the cases studied. Of 771 cases of melanoma reviewed, lentigo maligna and lentigo maligna melanoma accounted for 429 (56%). There were 220 cases of pagetoid (superficial spreading) melanoma (29%). Nodular melanoma with no apparent radial growth phase accounted for 27 cases (4%), and there were 23 cases of acral lentiginous melanoma (3%). The remaining 72 specimens (9%) included cutaneous metastases, spitzoid melanoma, melanoma in situ arising within a nevus, nevoid melanoma, desmoplastic melanoma, and patterns that could not be classified. LIMITATIONS: Although the dermatopathology practice is located in South Texas, most patients are active duty military, military retirees, and military dependents. The majority currently resides in Texas, but the patients have lived in many locations around the world and traveled extensively. Sun exposure patterns and other risk factors may not reflect those of other populations. We were not able to perform subgroup analysis based on ethnicity or skin type as such data were not typically submitted with the specimens. CONCLUSION: Our results challenge the notion that pagetoid (superficial spreading) melanoma is the most common subtype of malignant melanoma, at least in patients with extensive sun exposure. Changing patterns of sun exposure or environmental factors may contribute to the changing epidemiology of malignant melanoma. The current prevalence of subtypes of melanoma should be studied in other populations.