Histologic Classification of the Undescended Testis

Description

An undescended testis in a prepubertal male can be classified based upon its histologic features.

Prepubertal testicular biopsy evaluation:

(1) tubular fertility index: count of tubular cross-sections containing germ cells of any sort

(2) diameter of seminiferous tubules in microns

(3) Sertoli cell index: number of Sertoli cells per tubular section

Undescended Testis Type	Tubular Fertility Index	Mean Tubular Diameter	Sertoli Cell Index
I	normal or slight reduction	normal	normal
II	marked reduction	slight to marked decrease	normal
III	severe reduction	diffuse and severe decrease	diffuse Sertoli cell hypoplasia
IV	variable	variable	diffuse Sertoli cell hyperplasia

Tubular fertility index (germinal hypoplasia)	Interpretation
> 50% of normal	slight
30 - 50%	marked
< 30%	severe

Mean tubular diameter (as percent of normal for age)	Interpretation
90+%	slight
70 - 90%	marked
< 70%	severe

Sertoli cell index:	Interpretation
10-12 Sertoli cells per tubule	normal
<= 67% of normal mean	hypoplasia
>= 133% of normal mean	hyperplasia

Age in Years	Mean Tubular Fertility Index (in per cent)
0 - 0.5	71
1	35
2	40
3	74
4	78
5	80
6	87
7	99
8	86
9	97
10
11	84
12	91
13
14	100
> 15	100

from Table 2 and 3, Farrington (1969)

Age in years	Mean Tubular Diameter in microns
0 - 0.5	80
1	57
2	68
3	66
4	73
5	61
6	77
7	72
8	87
9	94
10	104
11
12	146
13
14	214
15
16	211
>= 17	230

after Table 1, Farrington (1969)

Limitations:

• Using mean values is problematic, since many of the studies use small numbers of subjects with the data sometimes showing large standard deviations.

• Different ages for the onset of puberty affected normal data.

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Description

Specialty

ICD-10